Astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
is the oldest of the
natural sciences, dating back to
antiquity, with its origins in the
religious
Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatur ...
,
mythological,
cosmological
Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...
,
calendrical, and
astrological
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Dif ...
beliefs and practices of
prehistory
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use ...
: vestiges of these are still found in
astrology
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Di ...
, a discipline long interwoven with public and governmental astronomy. It was not completely separated in Europe (see
astrology and astronomy
Astrology and astronomy were archaically treated together ( la, astrologia), but gradually distinguished through the Late Middle Ages into the Age of Reason. Developments in 17th century philosophy resulted in astrology and astronomy operating a ...
) during the Copernican Revolution starting in 1543. In some cultures, astronomical data was used for astrological prognostication.
Early history
Early
culture
Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
s identified celestial objects with
god
In monotheistic thought, God is usually viewed as the supreme being, creator, and principal object of faith. Swinburne, R.G. "God" in Honderich, Ted. (ed)''The Oxford Companion to Philosophy'', Oxford University Press, 1995. God is typically ...
s and spirits. They related these objects (and their movements) to phenomena such as
rain
Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water ...
,
drought
A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...
,
season
A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and ...
s, and
tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
s. It is generally believed that the first astronomers were
priest
A priest is a religious leader authorized to perform the sacred rituals of a religion, especially as a mediatory agent between humans and one or more deities. They also have the authority or power to administer religious rites; in partic ...
s, and that they understood
celestial objects
An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''body'' are often us ...
and events to be manifestations of the
divine
Divinity or the divine are things that are either related to, devoted to, or proceeding from a deity.[divine< ...](_blank)
, hence early astronomy's connection to what is now called
astrology
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Di ...
. A 32,500-year-old carved ivory
mammoth
A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks an ...
tusk could contain the oldest known star chart (resembling the
constellation Orion). It has also been suggested that drawing on the wall of the
Lascaux
Lascaux ( , ; french: Grotte de Lascaux , "Lascaux Cave") is a network of caves near the village of Montignac, in the department of Dordogne in southwestern France. Over 600 parietal wall paintings cover the interior walls and ceilings of ...
caves in France dating from 33,000 to 10,000 years ago could be a graphical representation of the
Pleiades
The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot B-type stars in the north-west of the constellation Taurus. At a distance ...
, the
Summer Triangle, and the
Northern Crown
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a ...
. Ancient structures with possibly
astronomical alignments (such as
Stonehenge) probably fulfilled astronomical,
religious
Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatur ...
, and
social function
Structural functionalism, or simply functionalism, is "a framework for building theory that sees society as a complex system whose parts work together to promote solidarity and stability".
This approach looks at society through a macro-level o ...
s.
Calendars of the world have often been set by observations of the Sun and Moon (marking the
day,
month and
year
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hou ...
), and were important to
agricultural societies, in which the harvest depended on planting at the correct time of year, and for which the nearly full moon was the only lighting for night-time travel into city markets.
The
common modern calendar is based on the
Roman calendar
The Roman calendar was the calendar used by the Roman Kingdom and Roman Republic. The term often includes the Julian calendar established by the reforms of the dictator Julius Caesar and emperor Augustus in the late 1stcenturyBC and sometim ...
. Although originally a
lunar calendar
A lunar calendar is a calendar based on the monthly cycles of the Moon's phases ( synodic months, lunations), in contrast to solar calendars, whose annual cycles are based only directly on the solar year. The most commonly used calendar, t ...
,
it broke the traditional link of the month to the phases of the Moon and divided the year into twelve almost-equal months, that mostly alternated between thirty and thirty-one days.
Julius Caesar
Gaius Julius Caesar (; ; 12 July 100 BC – 15 March 44 BC), was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in a civil war, ...
instigated
calendar reform
Calendar reform or calendrical reform is any significant revision of a calendar system. The term sometimes is used instead for a proposal to switch to a different calendar design.
Principles
The prime objective of a calendar is to unambiguo ...
in 46
BCE
Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the or ...
and introduced what is now called the
Julian calendar
The Julian calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on , by edict. It was designed with the aid of Greek mathematicians and astronomers such as Sosigenes of Alexandr ...
, based upon the
365 day year length originally proposed by the 4th century
BCE
Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the or ...
Greek astronomer
Callippus
Callippus (; grc, Κάλλιππος; c. 370 BC – c. 300 BC) was a Greek astronomer and mathematician.
Biography
Callippus was born at Cyzicus, and studied under Eudoxus of Cnidus at the Academy of Plato. He also worked with Aristotle at th ...
.
Prehistoric Europe
Since 1990 our understanding of prehistoric Europeans has been radically changed by discoveries of ancient astronomical artifacts throughout
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
. The artifacts demonstrate that Neolithic and Bronze Age Europeans had a sophisticated knowledge of
mathematics and astronomy.
Among the discoveries are:
*Paleolithic archaeologist
Alexander Marshack Alexander Marshack (April 4, 1918 – December 20, 2004) was an American independent scholar and Paleolithic archaeologist. He was born in The Bronx and earned a bachelor's degree in journalism from City College of New York, and worked for many y ...
put forward a theory in 1972 that bone sticks from locations like Africa and Europe from possibly as long ago as 35,000 BCE could be marked in ways that tracked the Moon's phases, an interpretation that has met with criticism.
*The
Warren Field calendar in the Dee River valley of
Scotland
Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...
's
Aberdeenshire. First
excavated in 2004 but only in 2013 revealed as a find of huge significance, it is to date the oldest known calendar, created around 8000 BC and predating all other calendars by some 5,000 years. The calendar takes the form of an early
Mesolithic monument containing a series of 12 pits which appear to help the observer track lunar months by mimicking the phases of the Moon. It also aligns to sunrise at the winter solstice, thus coordinating the solar year with the lunar cycles. The monument had been maintained and periodically reshaped, perhaps up to hundreds of times, in response to shifting solar/lunar cycles, over the course of 6,000 years, until the calendar fell out of use around 4,000 years ago.
*
Goseck circle is located in
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
and belongs to the
linear pottery culture. First discovered in 1991, its significance was only clear after results from archaeological digs became available in 2004. The site is one of hundreds of similar
circular enclosures built in a region encompassing
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
,
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
, and the
Czech Republic
The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...
during a 200-year period starting shortly after 5000 BC.
*The
Nebra sky disc is a
Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...
bronze disc that was buried in Germany, not far from the Goseck circle, around 1600 BC. It measures about 30 cm diameter with a mass of 2.2 kg and displays a blue-green patina (from oxidization) inlaid with gold symbols. Found by archeological thieves in 1999 and recovered in Switzerland in 2002, it was soon recognized as a spectacular discovery, among the most important of the 20th century. Investigations revealed that the object had been in use around 400 years before burial (2000 BC), but that its use had been forgotten by the time of burial. The inlaid gold depicted the full moon, a crescent moon about 4 or 5 days old, and the
Pleiades
The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot B-type stars in the north-west of the constellation Taurus. At a distance ...
star cluster in a specific arrangement forming the earliest known depiction of celestial phenomena. Twelve lunar months pass in 354 days, requiring a calendar to insert a leap month every two or three years in order to keep synchronized with the solar year's seasons (making it
lunisolar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the E ...
). The earliest known descriptions of this coordination were recorded by the Babylonians in 6th or 7th centuries BC, over one thousand years later. Those descriptions verified ancient knowledge of the Nebra sky disc's celestial depiction as the precise arrangement needed to judge when to insert the
intercalary month into a lunisolar calendar, making it an astronomical clock for regulating such a calendar a thousand or more years before any other known method.
*The
Kokino site, discovered in 2001, sits atop an extinct
volcanic cone
Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and ...
at an elevation of , occupying about 0.5 hectares overlooking the surrounding countryside in
North Macedonia
North Macedonia, ; sq, Maqedonia e Veriut, (Macedonia before February 2019), officially the Republic of North Macedonia,, is a country in Southeast Europe. It gained independence in 1991 as one of the successor states of Yugoslavia. It ...
. A
Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...
astronomical observatory was constructed there around 1900 BC and continuously served the nearby community that lived there until about 700 BC. The central space was used to observe the rising of the Sun and full moon. Three markings locate sunrise at the summer and winter solstices and at the two equinoxes. Four more give the minimum and maximum declinations of the full moon: in summer, and in winter. Two measure the lengths of lunar months. Together, they reconcile solar and lunar cycles in marking the 235
lunation
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month.
Variations
In Shona, Middle Eastern, and Euro ...
s that occur during 19 solar years, regulating a lunar calendar. On a platform separate from the central space, at lower elevation, four stone seats (thrones) were made in north-south alignment, together with a trench marker cut in the eastern wall. This marker allows the rising Sun's light to fall on only the second throne, at midsummer (about July 31). It was used for ritual ceremony linking the ruler to the local sun god, and also marked the end of the growing season and time for harvest.
*
Golden hat
Golden hats (or gold hats) (german: Goldhüte, singular: ) are a very specific and rare type of archaeological artifact from Bronze Age Europe. So far, four such objects ("cone-shaped gold hats of the Schifferstadt type") are known. The objec ...
s of Germany,
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
and
Switzerland dating from 1400–800 BC are associated with the Bronze Age
Urnfield culture
The Urnfield culture ( 1300 BC – 750 BC) was a late Bronze Age culture of Central Europe, often divided into several local cultures within a broader Urnfield tradition. The name comes from the custom of cremating the dead and p ...
. The Golden hats are decorated with a spiral
motif of the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
and the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
. They were probably a kind of
calendar used to
calibrate
In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...
between the
lunar
Lunar most commonly means "of or relating to the Moon".
Lunar may also refer to:
Arts and entertainment
* ''Lunar'' (series), a series of video games
* "Lunar" (song), by David Guetta
* "Lunar", a song by Priestess from the 2009 album ''Prior t ...
and
solar calendars. Modern
scholarship
A scholarship is a form of financial aid awarded to students for further education. Generally, scholarships are awarded based on a set of criteria such as academic merit, diversity and inclusion, athletic skill, and financial need.
Scholars ...
has demonstrated that the ornamentation of the gold leaf cones of the
Schifferstadt type, to which the
Berlin Gold Hat example belongs, represent systematic sequences in terms of number and types of ornaments per band. A detailed study of the Berlin example, which is the only fully preserved one, showed that the symbols probably represent a
lunisolar
A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the E ...
calendar. The object would have permitted the determination of dates or periods in both
lunar
Lunar most commonly means "of or relating to the Moon".
Lunar may also refer to:
Arts and entertainment
* ''Lunar'' (series), a series of video games
* "Lunar" (song), by David Guetta
* "Lunar", a song by Priestess from the 2009 album ''Prior t ...
and
solar calendars.
[Wilfried Menghin (Hrsg.): ''Acta Praehistorica et Archaeologica.'' Unze, Potsdam 32.2000, S. 31–108. ]
Ancient times
Mesopotamia
The origins of
Western
Western may refer to:
Places
*Western, Nebraska, a village in the US
*Western, New York, a town in the US
*Western Creek, Tasmania, a locality in Australia
*Western Junction, Tasmania, a locality in Australia
*Western world, countries that id ...
astronomy can be found in
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
, the "land between the rivers"
Tigris
The Tigris () is the easternmost of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of the Armenian Highlands through the Syrian and Arabian Deserts, and empties into the ...
and
Euphrates
The Euphrates () is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia ( ''the land between the rivers''). Originating in Turkey, the Eup ...
, where the ancient kingdoms of
Sumer,
Assyria
Assyria ( Neo-Assyrian cuneiform: , romanized: ''māt Aššur''; syc, ܐܬܘܪ, ʾāthor) was a major ancient Mesopotamian civilization which existed as a city-state at times controlling regional territories in the indigenous lands of the ...
, and
Babylonia were located. A form of writing known as
cuneiform
Cuneiform is a logo-syllabic script that was used to write several languages of the Ancient Middle East. The script was in active use from the early Bronze Age until the beginning of the Common Era. It is named for the characteristic wedge-sh ...
emerged among the Sumerians around 3500–3000 BC. Our knowledge of Sumerian astronomy is indirect, via the earliest Babylonian star catalogues dating from about 1200 BC. The fact that many star names appear in Sumerian suggests a continuity reaching into the Early Bronze Age.
Astral theology
Astrotheology, astral mysticism, astral religion, astral or stellar theology (also referred to as astral or star worship) is the worship of the stars (individually or together as the night sky), the planets, and other heavenly bodies as deities, ...
, which gave planetary gods an important role in
Mesopotamian mythology
Mesopotamian mythology refers to the myths, religious texts, and other literature that comes from the region of ancient Mesopotamia which is a historical region of Western Asia, situated within the Tigris–Euphrates river system that occupies ...
and
religion
Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, ...
, began with the
Sumerians
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is one of the cradles of c ...
. They also used a
sexagesimal
Sexagesimal, also known as base 60 or sexagenary, is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form ...
(base 60) place-value number system, which simplified the task of recording very large and very small numbers. The modern practice of dividing a circle into 360
degrees, or an hour into 60 minutes, began with the Sumerians. For more information, see the articles on
Babylonian numerals
Assyro-Chaldean Babylonian cuneiform numerals were written in cuneiform, using a wedge-tipped reed stylus to make a mark on a soft clay tablet which would be exposed in the sun to harden to create a permanent record.
The Babylonians, who were fam ...
and
mathematics.
Classical sources frequently use the term
Chaldeans for the astronomers of Mesopotamia, who were, in reality, priest-scribes specializing in
astrology
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Di ...
and other forms of
divination.
The first evidence of recognition that astronomical phenomena are periodic and of the application of mathematics to their prediction is Babylonian. Tablets dating back to the
Old Babylonian period
The Old Babylonian Empire, or First Babylonian Empire, is dated to BC – BC, and comes after the end of Sumerian power with the destruction of the Third Dynasty of Ur, and the subsequent Isin-Larsa period. The chronology of the first dynasty ...
document the application of mathematics to the variation in the length of daylight over a solar year. Centuries of Babylonian observations of celestial phenomena are recorded in the series of
cuneiform
Cuneiform is a logo-syllabic script that was used to write several languages of the Ancient Middle East. The script was in active use from the early Bronze Age until the beginning of the Common Era. It is named for the characteristic wedge-sh ...
tablets known as the ''
Enūma Anu Enlil''. The oldest significant astronomical text that we possess is Tablet 63 of the ''Enūma Anu Enlil'', the
Venus tablet of
Ammi-saduqa Ammi-Saduqa (or Ammisaduqa, Ammizaduga) was a king, c. 1646–1626 BC according to the Middle Chronology dating, (or c. 1582–1562 according to the Short Chronology), of the First Dynasty of Babylon. Some twenty-one year-names survive for his rei ...
, which lists the first and last visible risings of Venus over a period of about 21 years and is the earliest evidence that the phenomena of a planet were recognized as periodic. The
MUL.APIN
MUL.APIN () is the conventional title given to a Babylonian compendium that deals with many diverse aspects of Babylonian astronomy and astrology.
It is in the tradition of earlier star catalogues, the so-called ''Three Stars Each'' lists, but ...
, contains catalogues of stars and constellations as well as schemes for predicting
heliacal risings and the settings of the planets, lengths of daylight measured by a
water clock
A water clock or clepsydra (; ; ) is a timepiece by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount is then measured.
Water clocks are one of the oldest time- ...
,
gnomon, shadows, and
intercalations. The Babylonian GU text arranges stars in 'strings' that lie along declination circles and thus measure right-ascensions or time-intervals, and also employs the stars of the zenith, which are also separated by given right-ascensional differences.
A significant increase in the quality and frequency of Babylonian observations appeared during the reign of
Nabonassar
Nabû-nāṣir was the king of Babylon from 747 to 734 BC. He deposed a foreign Chaldean usurper named Nabu-shuma-ishkun, bringing native rule back to Babylon after twenty-three years of Chaldean rule. His reign saw the beginning of a new era ...
(747–733 BC). The systematic records of ominous phenomena in
Babylonian astronomical diaries
The Babylonian astronomical diaries are a collection of Babylonian cuneiform texts that contain systematic records of astronomical observations and political events as well as predictions, based on astronomical observations. They also include othe ...
that began at this time allowed for the discovery of a repeating 18-year cycle of
lunar eclipses, for example. The Greek astronomer
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance ...
later used Nabonassar's reign to fix the beginning of an era, since he felt that the earliest usable observations began at this time.
The last stages in the development of Babylonian astronomy took place during the time of the
Seleucid Empire (323–60 BC). In the 3rd century BC, astronomers began to use "goal-year texts" to predict the motions of the planets. These texts compiled records of past observations to find repeating occurrences of ominous phenomena for each planet. About the same time, or shortly afterwards, astronomers created mathematical models that allowed them to predict these phenomena directly, without consulting past records. A notable Babylonian astronomer from this time was
Seleucus of Seleucia
Seleucus of Seleucia ( el, Σέλευκος ''Seleukos''; born c. 190 BC; fl. c. 150 BC) was a Hellenistic astronomer and philosopher. Coming from Seleucia on the Tigris, Mesopotamia, the capital of the Seleucid Empire, or, alternatively, Seleuk ...
, who was a supporter of the
heliocentric model
Heliocentrism (also known as the Heliocentric model) is the astronomical model in which the Earth and planets revolve around the Sun at the center of the universe. Historically, heliocentrism was opposed to geocentrism, which placed the Earth a ...
.
Babylonian astronomy was the basis for much of what was done in
Greek and Hellenistic astronomy, in classical
Indian astronomy
Astronomy has long history in Indian subcontinent stretching from pre-historic to modern times. Some of the earliest roots of Indian astronomy can be dated to the period of Indus Valley civilisation or earlier. Astronomy later developed as a dis ...
, in Sassanian Iran, in Byzantium, in Syria, in
Islamic astronomy
Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language. These developments mostly took place in the Middle ...
, in Central Asia, and in Western Europe.
India
Astronomy in the Indian subcontinent dates back to the period of
Indus Valley Civilisation
The Indus Valley Civilisation (IVC), also known as the Indus Civilisation was a Bronze Age civilisation in the northwestern regions of South Asia, lasting from 3300 BCE to 1300 BCE, and in its mature form 2600 BCE to 1900& ...
during 3rd millennium BCE, when it was used to create calendars.
As the Indus Valley civilization did not leave behind written documents, the oldest extant Indian astronomical text is the
Vedanga Jyotisha
Vedanga Jyotisha (), or Jyotishavedanga (), is one of earliest known Indian texts on astrology (''Jyotisha''). The extant text is dated to the final centuries BCE, but it may be based on a tradition reaching back to about 700-600 BCE.
The text ...
, dating from the
Vedic period
The Vedic period, or the Vedic age (), is the period in the late Bronze Age and early Iron Age of the history of India when the Vedic literature, including the Vedas (ca. 1300–900 BCE), was composed in the northern Indian subcontinent, betwe ...
.
The Vedanga Jyotisha is attributed to Lagadha and has an internal date of approximately 1350 b.c, and describes rules for tracking the motions of the Sun and the Moon for the purposes of ritual. It is available in two recensions, one belonging to the Rig Veda, and the other to the Yajur Veda. According to the Vedanga Jyotisha, in a ''yuga'' or "era", there are 5 solar years, 67 lunar sidereal cycles, 1,830 days, 1,835 sidereal days and 62 synodic months. During the 6th century, astronomy was influenced by the Greek and Byzantine astronomical traditions.
Aryabhata
Aryabhata ( ISO: ) or Aryabhata I (476–550 CE) was an Indian mathematician and astronomer of the classical age of Indian mathematics and Indian astronomy. He flourished in the Gupta Era and produced works such as the ''Aryabhatiya'' (which ...
(476–550), in his magnum opus ''
Aryabhatiya'' (499), propounded a computational system based on a planetary model in which the Earth was taken to be
spinning on its axis and the periods of the planets were given with respect to the Sun. He accurately calculated many astronomical constants, such as the periods of the planets, times of the
solar and
lunar
Lunar most commonly means "of or relating to the Moon".
Lunar may also refer to:
Arts and entertainment
* ''Lunar'' (series), a series of video games
* "Lunar" (song), by David Guetta
* "Lunar", a song by Priestess from the 2009 album ''Prior t ...
eclipses, and the instantaneous motion of the Moon.
[Joseph (2000).] Early followers of Aryabhata's model included
Varāhamihira
Varāhamihira ( 505 – 587), also called Varāha or Mihira, was an ancient Indian astrologer, astronomer, and polymath who lived in Ujjain (Madhya Pradesh, India). He was born at Kapitba in a Brahmin family, in the Avanti region, roughly co ...
,
Brahmagupta, and
Bhāskara II.
Astronomy was advanced during the
Shunga Empire and many
star catalogues were produced during this time. The Shunga period is known as the "Golden age of astronomy in India".
It saw the development of calculations for the motions and places of various planets, their rising and setting,
conjunctions, and the calculation of eclipses.
Indian astronomers by the 6th century believed that comets were celestial bodies that re-appeared periodically. This was the view expressed in the 6th century by the astronomers
Varahamihira and Bhadrabahu, and the 10th-century astronomer
Bhattotpala listed the names and estimated periods of certain comets, but it is unfortunately not known how these figures were calculated or how accurate they were.
Bhāskara II (1114–1185) was the head of the astronomical observatory at Ujjain, continuing the mathematical tradition of Brahmagupta. He wrote the ''Siddhantasiromani'' which consists of two parts: ''Goladhyaya'' (sphere) and ''Grahaganita'' (mathematics of the planets). He also calculated the time taken for the Earth to orbit the Sun to 9 decimal places. The Buddhist University of
Nalanda at the time offered formal courses in astronomical studies.
Other important astronomers from India include
Madhava of Sangamagrama
Iriññāttappiḷḷi Mādhavan known as Mādhava of Sangamagrāma () was an Indian mathematician and astronomer from the town believed to be present-day Kallettumkara, Aloor Panchayath, Irinjalakuda in Thrissur District, Kerala, India. He ...
,
Nilakantha Somayaji
Keļallur Nilakantha Somayaji (14 June 1444 – 1544), also referred to as Keļallur Comatiri, was a major mathematician and astronomer of the Kerala school of astronomy and mathematics. One of his most influential works was the comprehens ...
and
Jyeshtadeva, who were members of the
Kerala school of astronomy and mathematics
The Kerala school of astronomy and mathematics or the Kerala school was a school of mathematics and astronomy founded by Madhava of Sangamagrama in Tirur, Malappuram, Kerala, India, which included among its members: Parameshvara, Neelakanta S ...
from the 14th century to the 16th century. Nilakantha Somayaji, in his ''Aryabhatiyabhasya'', a commentary on Aryabhata's ''Aryabhatiya'', developed his own computational system for a partially
heliocentric planetary model, in which Mercury, Venus,
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
,
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
and
Saturn orbit the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, which in turn orbits the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, similar to the
Tychonic system
The Tychonic system (or Tychonian system) is a model of the Universe published by Tycho Brahe in the late 16th century, which combines what he saw as the mathematical benefits of the Copernican system with the philosophical and "physical" bene ...
later proposed by
Tycho Brahe
Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was ...
in the late 16th century. Nilakantha's system, however, was mathematically more efficient than the Tychonic system, due to correctly taking into account the equation of the centre and
latitudinal
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
motion of Mercury and Venus. Most astronomers of the
Kerala school of astronomy and mathematics
The Kerala school of astronomy and mathematics or the Kerala school was a school of mathematics and astronomy founded by Madhava of Sangamagrama in Tirur, Malappuram, Kerala, India, which included among its members: Parameshvara, Neelakanta S ...
who followed him accepted his planetary model.
[George G. Joseph (2000), ''The Crest of the Peacock: Non-European Roots of Mathematics'', 2nd edition, p. 408, Penguin Books, London, ]
Greece and Hellenistic world
The
Ancient Greeks
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
developed astronomy, which they treated as a branch of mathematics, to a highly sophisticated level. The first geometrical, three-dimensional models to explain the apparent motion of the planets were developed in the 4th century BC by
Eudoxus of Cnidus and
Callippus of Cyzicus. Their models were based on nested homocentric spheres centered upon the Earth. Their younger contemporary
Heraclides Ponticus proposed that the Earth rotates around its axis.
A different approach to celestial phenomena was taken by natural philosophers such as
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
and
Aristotle
Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
. They were less concerned with developing mathematical predictive models than with developing an explanation of the reasons for the motions of the Cosmos. In his ''Timaeus'', Plato described the universe as a spherical body divided into circles carrying the planets and governed according to harmonic intervals by a
world soul. Aristotle, drawing on the mathematical model of Eudoxus, proposed that the universe was made of a complex system of concentric
spheres
The Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES) are a series of miniaturized satellites developed by MIT's Space Systems Laboratory for NASA and US Military, to be used as a low-risk, extensible test bed for the ...
, whose circular motions combined to carry the planets around the earth. This basic cosmological model prevailed, in various forms, until the 16th century.
In the 3rd century BC
Aristarchus of Samos was the first to suggest a
heliocentric system, although only fragmentary descriptions of his idea survive.
Eratosthenes estimated the
circumference of the Earth with great accuracy (see also:
history of geodesy
The history of geodesy deals with the historical development of measurements and representations of the Earth. The corresponding scientific discipline, '' geodesy'' ( /dʒiːˈɒdɪsi/), began in pre-scientific antiquity and blossomed during th ...
).
Greek geometrical astronomy developed away from the model of concentric spheres to employ more complex models in which an
eccentric circle would carry around a smaller circle, called an
epicycle
In the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle (, meaning "circle moving on another circle") was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, S ...
which in turn carried around a planet. The first such model is attributed to
Apollonius of Perga and further developments in it were carried out in the 2nd century BC by
Hipparchus of Nicea. Hipparchus made a number of other contributions, including the first measurement of
precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In oth ...
and the compilation of the first star catalog in which he proposed our modern system of
apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...
s.
The
Antikythera mechanism
The Antikythera mechanism ( ) is an Ancient Greek hand-powered orrery, described as the oldest example of an analogue computer used to predict astronomical positions and eclipses decades in advance. It could also be used to track the four-yea ...
, an
ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...
astronomical observational device for calculating the movements of the Sun and the Moon, possibly the planets, dates from about 150–100 BC, and was the first ancestor of an astronomical
computer. It was discovered in an ancient shipwreck off the Greek island of
Antikythera
Antikythera or Anticythera ( ) is a Greek island lying on the edge of the Aegean Sea, between Crete and Peloponnese. In antiquity the island was known as (). Since the 2011 local government reform it is part of the municipality of Kythira isl ...
, between
Kythera
Kythira (, ; el, Κύθηρα, , also transliterated as Cythera, Kythera and Kithira) is an island in Greece lying opposite the south-eastern tip of the Peloponnese peninsula. It is traditionally listed as one of the seven main Ionian Islands, ...
and
Crete
Crete ( el, Κρήτη, translit=, Modern: , Ancient: ) is the largest and most populous of the Greek islands, the 88th largest island in the world and the fifth largest island in the Mediterranean Sea, after Sicily, Sardinia, Cyprus, ...
. The device became famous for its use of a
differential gear
A differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average.
Functional description
The following descr ...
, previously believed to have been invented in the 16th century, and the miniaturization and complexity of its parts, comparable to a clock made in the 18th century. The original mechanism is displayed in the Bronze collection of the
National Archaeological Museum of Athens, accompanied by a replica.
Depending on the historian's viewpoint, the acme or corruption of physical Greek astronomy is seen with
Ptolemy of Alexandria
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance ...
, who wrote the classic comprehensive presentation of geocentric astronomy, the ''Megale Syntaxis'' (Great Synthesis), better known by its Arabic title ''
Almagest'', which had a lasting effect on astronomy up to the
Renaissance
The Renaissance ( , ) , from , with the same meanings. is a period in European history
The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...
. In his ''Planetary Hypotheses'', Ptolemy ventured into the realm of cosmology, developing a physical model of his geometric system, in a universe many times smaller than the more realistic conception of
Aristarchus of Samos four centuries earlier.
Egypt
The precise orientation of the
Egyptian pyramids affords a lasting demonstration of the high degree of technical skill in watching the heavens attained in the 3rd millennium BC. It has been shown the Pyramids were aligned towards the
pole star
A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body.
Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its ...
, which, because of the
precession of the equinoxes
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In partic ...
, was at that time
Thuban
Thuban (), with Bayer designation Alpha Draconis or α Draconis, is a binary star system in the northern constellation of Draco. A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically signi ...
, a faint star in the constellation of
Draco
Draco is the Latin word for serpent or dragon.
Draco or Drako may also refer to:
People
* Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived
* ...
. Evaluation of the site of the temple of
Amun-Re
Amun (; also ''Amon'', ''Ammon'', ''Amen''; egy, jmn, reconstructed as (Old Egyptian and early Middle Egyptian) → (later Middle Egyptian) → (Late Egyptian), cop, Ⲁⲙⲟⲩⲛ, Amoun) romanized: ʾmn) was a major ancient Egyptian ...
at
Karnak
The Karnak Temple Complex, commonly known as Karnak (, which was originally derived from ar, خورنق ''Khurnaq'' "fortified village"), comprises a vast mix of decayed temples, pylons, chapels, and other buildings near Luxor, Egypt. Constr ...
, taking into account the change over time of the
obliquity of the ecliptic
In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and o ...
, has shown that the Great Temple was aligned on the rising of the
midwinter
Midwinter is the middle of the winter. The term is attested in the early Germanic calendars.
Attestations
Midwinter is attested in the early Germanic calendars, where it appears to have been a specific day or a number of days during the winter ha ...
Sun. The length of the corridor down which sunlight would travel would have limited illumination at other times of the year. The Egyptians also found the position of Sirius (the dog star) who they believed was Anubis, their Jackal headed god, moving through the heavens. Its position was critical to their civilisation as when it rose heliacal in the east before sunrise it foretold the flooding of the Nile. It is also the origin of the phrase 'dog days of summer' from.
Astronomy played a considerable part in
religious
Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatur ...
matters for fixing the dates of festivals and determining the hours of the
night
Night (also described as night time, unconventionally spelled as "nite") is the period of ambient darkness from sunset to sunrise during each 24-hour day, when the Sun is below the horizon. The exact time when night begins and ends depends ...
. The titles of several temple books are preserved recording the movements and phases of the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
,
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
and
stars. The rising of
Sirius
Sirius is the brightest star in the night sky. Its name is derived from the Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CM ...
(
Egyptian
Egyptian describes something of, from, or related to Egypt.
Egyptian or Egyptians may refer to:
Nations and ethnic groups
* Egyptians, a national group in North Africa
** Egyptian culture, a complex and stable culture with thousands of years of ...
: Sopdet,
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
: Sothis) at the beginning of the inundation was a particularly important point to fix in the yearly calendar.
Writing in the
Roman era
In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
,
Clement of Alexandria
Titus Flavius Clemens, also known as Clement of Alexandria ( grc , Κλήμης ὁ Ἀλεξανδρεύς; – ), was a Christian theologian and philosopher who taught at the Catechetical School of Alexandria. Among his pupils were Origen an ...
gives some idea of the importance of astronomical observations to the sacred rites:
And after the Singer advances the Astrologer (ὡροσκόπος), with a ''horologium'' (ὡρολόγιον) in his hand, and a ''palm'' (φοίνιξ), the symbols of astrology
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Di ...
. He must know by heart the Hermetic
Hermetic or related forms may refer to:
* of or related to the ancient Greek Olympian god Hermes
* of or related to Hermes Trismegistus, a legendary Hellenistic figure based on the Greek god Hermes and the Egyptian god Thoth
** , the ancient and m ...
astrological books, which are four in number. Of these, one is about the arrangement of the fixed stars that are visible; one on the positions of the Sun and Moon and five planets; one on the conjunctions and phases of the Sun and Moon; and one concerns their risings.
The Astrologer's instruments (''horologium'' and ''palm'') are a
plumb line
A plumb bob, plumb bob level, or plummet, is a weight, usually with a pointed tip on the bottom, suspended from a string and used as a vertical reference line, or plumb-line. It is a precursor to the spirit level and used to establish a vertic ...
and sighting instrument. They have been identified with two inscribed objects in the
Berlin Museum; a short handle from which a plumb line was hung, and a palm branch with a sight-slit in the broader end. The latter was held close to the eye, the former in the other hand, perhaps at arm's length. The "Hermetic" books which Clement refers to are the Egyptian theological texts, which probably have nothing to do with
Hellenistic
In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in ...
Hermetism
Hermeticism, or Hermetism, is a philosophical system that is primarily based on the purported teachings of Hermes Trismegistus (a legendary Hellenistic combination of the Greek god Hermes and the Egyptian god Thoth). These teachings are containe ...
.
From the tables of stars on the ceiling of the tombs of
Rameses VI and
Rameses IX
Neferkare Setepenre Ramesses IX (also written Ramses) (originally named Amon-her-khepshef Khaemwaset) (ruled 1129–1111 BC) was the eighth pharaoh of the Twentieth Dynasty of Egypt. He was the third longest serving king of this Dynasty after R ...
it seems that for fixing the hours of the night a man seated on the ground faced the Astrologer in such a position that the line of observation of the
pole star
A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body.
Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its ...
passed over the middle of his head. On the different days of the year each hour was determined by a fixed star
culminating or nearly culminating in it, and the position of these stars at the time is given in the tables as in the centre, on the left eye, on the right shoulder, etc. According to the texts, in founding or rebuilding temples the
north
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography.
Etymology
The word ''north ...
axis was determined by the same apparatus, and we may conclude that it was the usual one for astronomical observations. In careful hands it might give results of a high degree of accuracy.
China
The astronomy of
East Asia
East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...
began in
China.
Solar term
A solar term is any of twenty-four periods in traditional Chinese lunisolar calendars that matches a particular astronomical event or signifies some natural phenomenon. The points are spaced 15° apart along the ecliptic and are used by lunisola ...
was completed in
Warring States period
The Warring States period () was an era in ancient Chinese history characterized by warfare, as well as bureaucratic and military reforms and consolidation. It followed the Spring and Autumn period and concluded with the Qin wars of conquest ...
. The knowledge of Chinese astronomy was introduced into East Asia.
Astronomy in China has a long history. Detailed records of astronomical observations were kept from about the 6th century BC, until the introduction of Western astronomy and the telescope in the 17th century. Chinese astronomers were able to precisely predict eclipses.
Much of early Chinese astronomy was for the purpose of timekeeping. The Chinese used a lunisolar calendar, but because the cycles of the Sun and the Moon are different, astronomers often prepared new calendars and made observations for that purpose.
Astrological divination was also an important part of astronomy. Astronomers took careful note of
"guest stars"(
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
: 客星;
pinyin
Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Chinese, Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally writte ...
: ''kèxīng'';
lit.: 'guest star') which suddenly appeared among the
fixed star
In astronomy, fixed stars ( la, stellae fixae) is a term to name the full set of glowing points, astronomical objects actually and mainly stars, that appear not to move relative to one another against the darkness of the night sky in the backg ...
s. They were the first to record a supernova, in the Astrological Annals of the Houhanshu in 185 AD. Also, the supernova that created the
Crab Nebula in 1054 is an example of a "guest star" observed by Chinese astronomers, although it was not recorded by their European contemporaries. Ancient astronomical records of phenomena like supernovae and comets are sometimes used in modern astronomical studies.
The world's first
star catalogue was made by
Gan De
Gan De (; fl. 4th century BC), also known as the Lord Gan (Gan Gong), was an ancient Chinese astronomer and astrologer born in the State of Qi. Along with Shi Shen, he is believed to be the first in history known by name to compile a star catal ...
, a
Chinese astronomer, in the 4th century BC.
Mesoamerica
Maya
Maya may refer to:
Civilizations
* Maya peoples, of southern Mexico and northern Central America
** Maya civilization, the historical civilization of the Maya peoples
** Maya language, the languages of the Maya peoples
* Maya (Ethiopia), a popul ...
astronomical
codices
The codex (plural codices ) was the historical ancestor of the modern book. Instead of being composed of sheets of paper, it used sheets of vellum, papyrus, or other materials. The term ''codex'' is often used for ancient manuscript books, with ...
include detailed tables for calculating
phases of the Moon
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the t ...
, the recurrence of eclipses, and the appearance and disappearance of
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
as morning and
evening star. The Maya based their
calendrics
A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a phys ...
in the carefully calculated cycles of the
Pleiades
The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot B-type stars in the north-west of the constellation Taurus. At a distance ...
, the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
,
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
,
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
,
Saturn,
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
, and also they had a precise description of the eclipses as depicted in the
Dresden Codex
The ''Dresden Codex'' is a Maya book, which was believed to be the oldest surviving book written in the Americas, dating to the 11th or 12th century. However, in September 2018 it was proven that the Maya Codex of Mexico, previously known as th ...
, as well as the ecliptic or zodiac, and the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
was crucial in their Cosmology. A number of important Maya structures are believed to have been oriented toward the extreme risings and settings of Venus. To the ancient Maya, Venus was the patron of war and many recorded battles are believed to have been timed to the motions of this planet.
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
is also mentioned in preserved astronomical codices and early
mythology
Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. Since "myth" is widely used to imply that a story is not objectively true, the identification of a narra ...
.
Although the
Maya calendar
The Maya calendar is a system of calendars used in pre-Columbian Mesoamerica and in many modern communities in the Guatemalan highlands, Veracruz, Oaxaca and Chiapas, Mexico.
The essentials of the Maya calendar are based upon a system which had ...
was not tied to the Sun,
John Teeple has proposed that the Maya calculated the
solar year
A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky of a celestial body of the Solar System such as the Earth, completing a full cycle of seasons; for example, the time f ...
to somewhat greater accuracy than the
Gregorian calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years dif ...
. Both astronomy and an intricate numerological scheme for the measurement of time were vitally important components of
Maya religion.
The Maya believed that the Earth was the center of all things, and that the stars, moons, and planets were gods. They believed that their movements were the gods traveling between the Earth and other celestial destinations. Many key events in Maya culture were timed around celestial events, in the belief that certain gods would be present.
Middle Ages
Middle East
The Arabic and the Persian world under
Islam had become highly cultured, and many important works of knowledge from
Greek astronomy
Greek astronomy is astronomy written in the Greek language in classical antiquity. Greek astronomy is understood to include the Ancient Greek, Hellenistic, Greco-Roman, and Late Antiquity eras. It is not limited geographically to Greece or to e ...
and
Indian astronomy
Astronomy has long history in Indian subcontinent stretching from pre-historic to modern times. Some of the earliest roots of Indian astronomy can be dated to the period of Indus Valley civilisation or earlier. Astronomy later developed as a dis ...
and Persian astronomy were translated into Arabic, used and stored in libraries throughout the area. An important contribution by Islamic astronomers was their emphasis on
observational astronomy
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical ...
. This led to the emergence of the first astronomical
observatories
An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...
in the
Muslim world
The terms Muslim world and Islamic world commonly refer to the Islamic community, which is also known as the Ummah. This consists of all those who adhere to the religious beliefs and laws of Islam or to societies in which Islam is practiced. I ...
by the early 9th century.
[, in Roshdi Rashed & Régis Morelon (1996), '']Encyclopedia of the History of Arabic Science
The ''Encyclopedia of the History of Arabic Science'' is a three-volume encyclopedia covering the history of Arabic contributions to science, mathematics and technology which had a marked influence on the Middle Ages in Europe. It is written by in ...
'', pp. 985–1007, Routledge
Routledge () is a British multinational publisher. It was founded in 1836 by George Routledge, and specialises in providing academic books, journals and online resources in the fields of the humanities, behavioural science, education, law ...
, London and New York. Zij
A zij ( fa, زيج, zīj) is an Islamic astronomical book that tabulates parameters used for astronomical calculations of the positions of the Sun, Moon, stars, and planets.
Etymology
The name ''zij'' is derived from the Middle Persian term ' ...
star catalogues were produced at these observatories.
In the 10th century,
Abd al-Rahman al-Sufi (Azophi) carried out observations on the
stars and described their positions,
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
s, brightness, and
colour
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are assoc ...
and drawings for each constellation in his ''
Book of Fixed Stars
The ''Book of Fixed Stars'' ( ar, كتاب صور الكواكب ', literally ''The Book of the Shapes of Stars'') is an astronomical text written by Abd al-Rahman al-Sufi (Azophi) around 964. Following the translation movement in the 9th centu ...
''. He also gave the first descriptions and pictures of "A Little Cloud" now known as the
Andromeda Galaxy
The Andromeda Galaxy (IPA: ), also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about approximately from Earth and the nearest large galaxy to the Milky Way. The gal ...
. He mentions it as lying before the mouth of a Big Fish, an Arabic
constellation. This "cloud" was apparently commonly known to the
Isfahan astronomers, very probably before 905 AD.
The first recorded mention of the
Large Magellanic Cloud was also given by al-Sufi.
In 1006,
Ali ibn Ridwan
Abu'l Hassan Ali ibn Ridwan Al-Misri () (c. 988 - c. 1061) was an Arab of Egyptian origin who was a physician, astrologer and astronomer, born in Giza.
He was a commentator on ancient Greek medicine, and in particular on Galen; his commentary ...
observed
SN 1006, the brightest
supernova in recorded history, and left a detailed description of the temporary star.
In the late 10th century, a huge observatory was built near
Tehran
Tehran (; fa, تهران ) is the largest city in Tehran Province and the capital of Iran. With a population of around 9 million in the city and around 16 million in the larger metropolitan area of Greater Tehran, Tehran is the most popul ...
,
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
, by the astronomer
Abu-Mahmud al-Khujandi
Abu Mahmud Hamid ibn al-Khidr al-Khojandi (known as Abu Mahmood Khojandi, Alkhujandi or al-Khujandi, Persian: ابومحمود خجندی, c. 940 - 1000) was a Muslim Transoxanian astronomer and mathematician born in Khujand (now part of Tajikista ...
who observed a series of
meridian
Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to
Science
* Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon
* ...
transits of the Sun, which allowed him to calculate the tilt of the Earth's axis relative to the Sun. He noted that measurements by earlier (Indian, then Greek) astronomers had found higher values for this angle, possible evidence that the axial tilt is not constant but was in fact decreasing. In 11th-century Persia,
Omar Khayyám compiled many tables and performed a reformation of the
calendar that was more accurate than the
Julian and came close to the
Gregorian.
Other Muslim advances in astronomy included the collection and correction of previous astronomical data, resolving significant problems in the
Ptolemaic model, the development of the universal latitude-independent
astrolabe by
Arzachel, the invention of numerous other astronomical instruments,
Ja'far Muhammad ibn Mūsā ibn Shākir's belief that the
heavenly bodies and
celestial spheres were subject to the same
physical law
Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) ...
s as
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, and the introduction of empirical testing by
Ibn al-Shatir
ʿAbu al-Ḥasan Alāʾ al‐Dīn ʿAlī ibn Ibrāhīm al-Ansari known as Ibn al-Shatir or Ibn ash-Shatir ( ar, ابن الشاطر; 1304–1375) was an Arab astronomer, mathematician and engineer. He worked as ''muwaqqit'' (موقت, religious t ...
, who produced the first model of
lunar
Lunar most commonly means "of or relating to the Moon".
Lunar may also refer to:
Arts and entertainment
* ''Lunar'' (series), a series of video games
* "Lunar" (song), by David Guetta
* "Lunar", a song by Priestess from the 2009 album ''Prior t ...
motion which matched physical observations.
Natural philosophy
Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics, that is, nature and the physical universe. It was dominant before the development of modern science.
From the ancient wo ...
(particularly
Aristotelian physics
Aristotelian physics is the form of natural science described in the works of the Greek philosopher Aristotle (384–322 BC). In his work ''Physics'', Aristotle intended to establish general principles of change that govern all natural bodies, b ...
) was separated from astronomy by
Ibn al-Haytham
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the pri ...
(Alhazen) in the 11th century, by Ibn al-Shatir in the 14th century, and Qushji in the 15th century.
[F. Jamil Ragep (2001), "Tusi and Copernicus: The Earth's Motion in Context", ''Science in Context'' 14 (1–2), p. 145–163. ]Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer.
Cambridge University Pre ...
.
Western Europe
After the significant contributions of Greek scholars to the development of astronomy, it entered a relatively static era in Western Europe from the Roman era through the 12th century. This lack of progress has led some astronomers to assert that nothing happened in Western European astronomy during the Middle Ages. Recent investigations, however, have revealed a more complex picture of the study and teaching of astronomy in the period from the 4th to the 16th centuries.
Western Europe
Western Europe is the western region of Europe. The region's countries and territories vary depending on context.
The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean ...
entered the Middle Ages with great difficulties that affected the continent's intellectual production. The advanced astronomical treatises of
classical antiquity
Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations of ...
were written in
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
, and with the decline of knowledge of that language, only simplified summaries and practical texts were available for study. The most influential writers to pass on this ancient tradition in
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
were
Macrobius,
Pliny
Pliny may refer to:
People
* Pliny the Elder (23–79 CE), ancient Roman nobleman, scientist, historian, and author of ''Naturalis Historia'' (''Pliny's Natural History'')
* Pliny the Younger (died 113), ancient Roman statesman, orator, w ...
,
Martianus Capella
Martianus Minneus Felix Capella (fl. c. 410–420) was a jurist, polymath and Latin prose writer of late antiquity, one of the earliest developers of the system of the seven liberal arts that structured early medieval education. He was a nati ...
, and
Calcidius
Calcidius (or Chalcidius) was a 4th-century philosopher (and possibly a Christians, Christian) who translated the first part (to 53c) of Plato's ''Timaeus (dialogue), Timaeus'' from Greek (language), Greek into Latin around the year 321 and provid ...
. In the 6th century Bishop
Gregory of Tours noted that he had learned his astronomy from reading Martianus Capella, and went on to employ this rudimentary astronomy to describe a method by which monks could determine the time of prayer at night by watching the stars.
In the 7th century the English monk
Bede of Jarrow
Bede ( ; ang, Bǣda , ; 672/326 May 735), also known as Saint Bede, The Venerable Bede, and Bede the Venerable ( la, Beda Venerabilis), was an English monk at the monastery of St Peter and its companion monastery of St Paul in the Kingdom o ...
published an influential text, ''
On the Reckoning of Time'', providing churchmen with the practical astronomical knowledge needed to compute the proper date of
Easter
Easter,Traditional names for the feast in English are "Easter Day", as in the '' Book of Common Prayer''; "Easter Sunday", used by James Ussher''The Whole Works of the Most Rev. James Ussher, Volume 4'') and Samuel Pepys''The Diary of Samuel ...
using a procedure called the ''
computus''. This text remained an important element of the education of clergy from the 7th century until well after the rise of the
Universities
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, ...
in the
12th century.
The range of surviving ancient Roman writings on astronomy and the teachings of Bede and his followers began to be studied in earnest during the
revival of learning sponsored by the emperor
Charlemagne
Charlemagne ( , ) or Charles the Great ( la, Carolus Magnus; german: Karl der Große; 2 April 747 – 28 January 814), a member of the Carolingian dynasty, was King of the Franks from 768, King of the Lombards from 774, and the first ...
. By the 9th century rudimentary techniques for calculating the position of the planets were circulating in Western Europe; medieval scholars recognized their flaws, but texts describing these techniques continued to be copied, reflecting an interest in the motions of the planets and in their astrological significance.
Building on this astronomical background, in the 10th century European scholars such as
Gerbert of Aurillac
Pope Sylvester II ( – 12 May 1003), originally known as Gerbert of Aurillac, was a French-born scholar and teacher who served as the bishop of Rome and ruled the Papal States from 999 to his death. He endorsed and promoted study of Arab and Gr ...
began to travel to Spain and Sicily to seek out learning which they had heard existed in the Arabic-speaking world. There they first encountered various practical astronomical techniques concerning the calendar and timekeeping, most notably those dealing with the
astrolabe. Soon scholars such as
Hermann of Reichenau
Blessed Hermann of Reichenau (18 July 1013– 24 September 1054), also known by other names, was an 11th-century Benedictine monk and scholar. He composed works on history, music theory, mathematics, and astronomy, as well as many hymns. ...
were writing texts in Latin on the uses and construction of the astrolabe and others, such as
Walcher of Malvern
Walcher of Malvern (died 1135) (also known as Walcher of Lorraine) was the second Prior of Great Malvern Priory in Worcestershire, England, and a noted astronomer, astrologer and mathematician. He has been described as an important transitional f ...
, were using the astrolabe to observe the time of eclipses in order to test the validity of computistical tables.
By the 12th century, scholars were traveling to Spain and Sicily to seek out more advanced astronomical and astrological texts, which they
translated into Latin from Arabic and Greek to further enrich the astronomical knowledge of Western Europe. The arrival of these new texts coincided with the rise of the universities in medieval Europe, in which they soon found a home. Reflecting the introduction of astronomy into the universities,
John of Sacrobosco
Johannes de Sacrobosco, also written Ioannes de Sacro Bosco, later called John of Holywood or John of Holybush ( 1195 – 1256), was a scholar, monk, and astronomer who taught at the University of Paris.
He wrote a short introduction to the Hi ...
wrote a series of influential introductory astronomy textbooks: the
Sphere
A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is th ...
, a Computus, a text on the
Quadrant, and another on Calculation.
In the 14th century,
Nicole Oresme
Nicole Oresme (; c. 1320–1325 – 11 July 1382), also known as Nicolas Oresme, Nicholas Oresme, or Nicolas d'Oresme, was a French philosopher of the later Middle Ages. He wrote influential works on economics, mathematics, physics, astrology an ...
, later bishop of Liseux, showed that neither the scriptural texts nor the physical arguments advanced against the movement of the Earth were demonstrative and adduced the argument of simplicity for the theory that the Earth moves, and ''not'' the heavens. However, he concluded "everyone maintains, and I think myself, that the heavens do move and not the earth: For God hath established the world which shall not be moved." In the 15th century, Cardinal
Nicholas of Cusa
Nicholas of Cusa (1401 – 11 August 1464), also referred to as Nicholas of Kues and Nicolaus Cusanus (), was a German Catholic cardinal, philosopher, theologian, jurist, mathematician, and astronomer. One of the first German proponents of Re ...
suggested in some of his scientific writings that the Earth revolved around the Sun, and that each star is itself a distant sun.
Renaissance and Early Modern Europe
Copernican Revolution
During the renaissance period, astronomy began to undergo a revolution in thought known as the
Copernican Revolution
The Copernican Revolution was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the Solar Sys ...
, which gets the name from the astronomer
Nicolaus Copernicus
Nicolaus Copernicus (; pl, Mikołaj Kopernik; gml, Niklas Koppernigk, german: Nikolaus Kopernikus; 19 February 1473 – 24 May 1543) was a Renaissance polymath, active as a mathematician, astronomer, and Catholic canon, who formulated ...
, who proposed a heliocentric system, in which the planets revolved around the Sun and not the Earth. His ''
De revolutionibus orbium coelestium
''De revolutionibus orbium coelestium'' (English translation: ''On the Revolutions of the Heavenly Spheres'') is the seminal work on the heliocentric theory of the astronomer Nicolaus Copernicus (1473–1543) of the Polish Renaissance. The book, ...
'' was published in 1543.
[Westman, Robert S. (2011). ''The Copernican Question: Prognostication, Skepticism, and Celestial Order''. Los Angeles: University of California Press. .] While in the long term this was a very controversial claim, in the very beginning it only brought minor controversy.
The theory became the dominant view because many figures, most notably
Galileo Galilei
Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He wa ...
,
Johannes Kepler and
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a " natural philosopher"), widely recognised as one of the grea ...
championed and improved upon the work. Other figures also aided this new model despite not believing the overall theory, like
Tycho Brahe
Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was ...
, with his well-known observations.
John Louis Emil Dreyer
John Louis Emil Dreyer (13 February 1852 – 14 September 1926) was a Danish astronomer who spent most of his career working in Ireland. He spent the last decade of his life in Oxford, England.
Life
Dreyer was born in Copenhagen. His fath ...
, ''Tycho Brahe: a Picture of Scientific Life and Work in the Sixteenth Century'', A. & C. Black (1890), pp. 162–3
Brahe, a Danish noble, was an essential astronomer in this period.
He came on the astronomical scene with the publication of ''De nova stella'', in which he disproved conventional wisdom on the supernova
SN 1572
SN 1572 ('' Tycho's Supernova'', ''Tycho's Nova''), or B Cassiopeiae (B Cas), was a supernova of Type Ia in the constellation Cassiopeia, one of eight supernovae visible to the naked eye in historical records. It appeared in early November 1572 ...
(As bright as Venus at its peak, SN 1572 later became invisible to the naked eye, disproving the
Aristotelian doctrine of the immutability of the heavens.)
He also created the
Tychonic system
The Tychonic system (or Tychonian system) is a model of the Universe published by Tycho Brahe in the late 16th century, which combines what he saw as the mathematical benefits of the Copernican system with the philosophical and "physical" bene ...
, where the Sun and Moon and the stars revolve around the Earth, but the other five planets revolve around the Sun. This system blended the mathematical benefits of the Copernican system with the "physical benefits" of the Ptolemaic system.
[ Westman, Robert S. (1975). ''The Copernican achievement''. University of California Press. p. 322. . OCLC 164221945.] This was one of the systems people believed in when they did not accept heliocentrism, but could no longer accept the Ptolemaic system.
He is most known for his highly accurate observations of the stars and the Solar System. Later he moved to Prague and continued his work. In Prague he was at work on the
Rudolphine Tables
The ''Rudolphine Tables'' ( la, Tabulae Rudolphinae) consist of a star catalogue and planetary tables published by Johannes Kepler in 1627, using observational data collected by Tycho Brahe (1546–1601). The tables are named in memory of Rudolf ...
, that were not finished until after his death.
[Athreya, A.; Gingerich, O. (December 1996). "An Analysis of Kepler's Rudolphine Tables and Implications for the Reception of His Physical Astronomy". ''Bulletin of the American Astronomical Society''. 28 (4): 1305.] The Rudolphine Tables was a star map designed to be more accurate than either the
Alfonsine tables, made in the 1300s, and the
Prutenic Tables
The ''Prutenic Tables'' ( la, Tabulae prutenicae from ''Prutenia'' meaning "Prussia", german: Prutenische oder Preußische Tafeln), were an ephemeris (astronomical tables) by the astronomer Erasmus Reinhold published in 1551 (reprinted in 1562, 1 ...
, which were inaccurate.
He was assisted at this time by his assistant Johannes Kepler, who would later use his observations to finish Brahe's works and for his theories as well.
After the death of Brahe, Kepler was deemed his successor and was given the job of completing Brahe's uncompleted works, like the Rudolphine Tables.
He completed the Rudolphine Tables in 1624, although it was not published for several years.
Like many other figures of this era, he was subject to religious and political troubles, like the
Thirty Years' War
The Thirty Years' War was one of the longest and most destructive conflicts in European history, lasting from 1618 to 1648. Fought primarily in Central Europe, an estimated 4.5 to 8 million soldiers and civilians died as a result of battle ...
, which led to chaos that almost destroyed some of his works. Kepler was, however, the first to attempt to derive mathematical predictions of celestial motions from assumed physical causes. He discovered the three
Kepler's laws of planetary motion that now carry his name, those laws being as follows:
#The orbit of a planet is an ellipse with the Sun at one of the two foci.
#A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
#The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
With these laws, he managed to improve upon the existing heliocentric model. The first two were published in 1609. Kepler's contributions improved upon the overall system, giving it more credibility because it adequately explained events and could cause more reliable predictions. Before this, the Copernican model was just as unreliable as the Ptolemaic model. This improvement came because Kepler realized the orbits were not perfect circles, but ellipses.
Galileo Galilei
Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He wa ...
was among the first to use a telescope to observe the sky, and after constructing a 20x refractor telescope. He discovered the four largest moons of Jupiter in 1610, which are now collectively known as the
Galilean moons, in his honor.
["Satellites of Jupiter". ''The Galileo Project''. ]Rice University
William Marsh Rice University (Rice University) is a private research university in Houston, Texas. It is on a 300-acre campus near the Houston Museum District and adjacent to the Texas Medical Center. Rice is ranked among the top universities ...
. 1995. This discovery was the first known observation of satellites orbiting another planet.
He also found that the Moon had craters and observed, and correctly explained sunspots, and that Venus exhibited a full set of phases resembling lunar phases.
Galileo argued that these facts demonstrated incompatibility with the Ptolemaic model, which could not explain the phenomenon and would even contradict it.
With the moons it demonstrated that the Earth does not have to have everything orbiting it and that other parts of the
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
could orbit another object, such as the Earth orbiting the Sun.
In the Ptolemaic system the celestial bodies were supposed to be perfect so such objects should not have craters or sunspots. The phases of Venus could only happen in the event that Venus' orbit is inside Earth's orbit, which could not happen if the Earth was the center. He, as the most famous example, had to face challenges from church officials, more specifically the
Roman Inquisition
The Roman Inquisition, formally the Supreme Sacred Congregation of the Roman and Universal Inquisition, was a system of partisan tribunals developed by the Holy See of the Roman Catholic Church, during the second half of the 16th century, respons ...
.
[Finnocchiaro, Maurice (1989). ''The Galileo Affair''. Berkeley and Los Angeles, California: University of California Press. p. 291.] They accused him of heresy because these beliefs went against the teachings of the Roman Catholic Church and were challenging the Catholic church's authority when it was at its weakest.
While he was able to avoid punishment for a little while he was eventually tried and pled guilty to heresy in 1633.
Although this came at some expense, his book was banned, and he was put under house arrest until he died in 1642.
Sir Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a " natural philosopher"), widely recognised as one of the g ...
developed further ties between physics and astronomy through his
law of universal gravitation. Realizing that the same force that attracts objects to the surface of the Earth held the Moon in orbit around the Earth, Newton was able to explain – in one theoretical framework – all known gravitational phenomena. In his ''
Philosophiæ Naturalis Principia Mathematica'', he derived Kepler's laws from first principles. Those first principles are as follows:
#In an
inertial frame of reference
In classical physics and special relativity, an inertial frame of reference (also called inertial reference frame, inertial frame, inertial space, or Galilean reference frame) is a frame of reference that is not undergoing any acceleration. ...
, an object either remains at rest or continues to move at constant
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...
, unless acted upon by a
force.
#In an inertial reference frame, the
vector sum
In mathematics, physics, and engineering, a Euclidean vector or simply a vector (sometimes called a geometric vector or spatial vector) is a geometric object that has magnitude (or length) and direction. Vectors can be added to other vectors a ...
of the forces F on an object is equal to the
mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...
m of that object multiplied by the
acceleration
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by t ...
a of the object: F = ma. (It is assumed here that the mass m is constant)
#When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Thus while Kepler explained how the planets moved, Newton accurately managed to explain why the planets moved the way they do. Newton's theoretical developments laid many of the foundations of modern physics.
Completing the Solar System
Outside of England, Newton's theory took some time to become established.
Descartes'
theory of vortices held sway in France, and
Huygens,
Leibniz
Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of ma ...
and
Cassini accepted only parts of Newton's system, preferring their own philosophies.
Voltaire
François-Marie Arouet (; 21 November 169430 May 1778) was a French Enlightenment writer, historian, and philosopher. Known by his ''nom de plume'' M. de Voltaire (; also ; ), he was famous for his wit, and his criticism of Christianity—es ...
published a popular account in 1738. In 1748, the
French Academy of Sciences offered a reward for solving the perturbations of Jupiter and Saturn which was eventually solved by
Euler and
Lagrange.
Laplace completed the theory of the planets, publishing from 1798 to 1825. The early origins of the
solar nebular model of planetary formation had begun.
Edmond Halley
Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720.
From an observatory he constructed on Saint Helena in 1676–77, H ...
succeeded
Flamsteed
John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called ''Atlas Coe ...
as
Astronomer Royal
Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834.
The post ...
in England and succeeded in predicting the return of the
comet that bears his name in 1758.
Sir William Herschel
Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...
found the first new planet,
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...
, to be observed in modern times in 1781. The gap between the planets Mars and Jupiter disclosed by the
Titius–Bode law
The Titius–Bode law (sometimes termed just Bode's law) is a formulaic prediction of spacing between planets in any given solar system. The formula suggests that, extending outward, each planet should be approximately twice as far from the Sun as ...
was filled by the discovery of the
asteroids
Ceres
Ceres most commonly refers to:
* Ceres (dwarf planet), the largest asteroid
* Ceres (mythology), the Roman goddess of agriculture
Ceres may also refer to:
Places
Brazil
* Ceres, Goiás, Brazil
* Ceres Microregion, in north-central Goiás ...
and
Pallas
Pallas may refer to:
Astronomy
* 2 Pallas asteroid
** Pallas family, a group of asteroids that includes 2 Pallas
* Pallas (crater), a crater on Earth's moon
Mythology
* Pallas (Giant), a son of Uranus and Gaia, killed and flayed by Athena
* Pa ...
in 1801 and 1802 with many more following.
At first,
astronomical thought in America was based on
Aristotelian philosophy, but interest in the new astronomy began to appear in
Almanacs
An almanac (also spelled ''almanack'' and ''almanach'') is an annual publication listing a set of current information about one or multiple subjects. It includes information like weather forecasts, farmers' planting dates, tide tables, and other ...
as early as 1659.
Stellar astronomy
Cosmic pluralism
Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the belief in numerous "worlds" (planets, dwarf planets or natural satellites) in addition to Earth (possibly an infinite number), which may harbour extraterrestrial life ...
is the name given to the idea that the stars are distant suns, perhaps with their own planetary systems.
Ideas in this direction were expressed in antiquity, by
Anaxagoras and by
Aristarchus of Samos, but did not find mainstream acceptance. The first astronomer of the European Renaissance to suggest that the stars were distant suns was
Giordano Bruno in his ''De l'infinito universo et mondi'' (1584). This idea was among the charges, albeit not in a prominent position, brought against him by the Inquisition.
The idea became mainstream in the later 17th century, especially following the publication of ''
Conversations on the Plurality of Worlds
''Conversations on the Plurality of Worlds'' (french: Entretiens sur la pluralité des mondes) is a popular science book by French author Bernard le Bovier de Fontenelle, published in 1686.
Content
The work consists of six lessons popularizing ...
'' by
Bernard Le Bovier de Fontenelle (1686), and by the early 18th century it was the default working assumptions in stellar astronomy.
The Italian astronomer
Geminiano Montanari
Geminiano Montanari (1 June 1633 – 13 October 1687) was an Italian astronomer, lens-maker, and proponent of the experimental approach to science. He was a member of various learned academies, notably the Accademia dei Gelati. Montanari's famous ...
recorded observing variations in luminosity of the star
Algol
ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the ...
in 1667. Edmond Halley published the first measurements of the
proper motion of a pair of nearby "fixed" stars, demonstrating that they had changed positions since the time of the ancient
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
astronomers Ptolemy and Hipparchus.
William Herschel
Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline ...
was the first astronomer to attempt to determine the distribution of stars in the sky. During the 1780s, he established a series of gauges in 600 directions and counted the stars observed along each line of sight. From this he deduced that the number of stars steadily increased toward one side of the sky, in the direction of the Milky Way
core
Core or cores may refer to:
Science and technology
* Core (anatomy), everything except the appendages
* Core (manufacturing), used in casting and molding
* Core (optical fiber), the signal-carrying portion of an optical fiber
* Core, the centra ...
. His son
John Herschel repeated this study in the southern hemisphere and found a corresponding increase in the same direction. In addition to his other accomplishments, William Herschel is noted for his discovery that some stars do not merely lie along the same line of sight, but are physical companions that form binary star systems.
Modern astronomy
19th century
Pre-photography, data recording of astronomical data was limited by the human eye. In 1840,
John W. Draper, a chemist, created the earliest known astronomical photograph of the Moon. And by the late 19th century thousands of photographic plates of images of planets, stars, and galaxies were created. Most photography had lower quantum efficiency (i.e. captured less of the incident photons) than human eyes but had the advantage of long integration times (100 ms for the human eye compared to hours for photos). This vastly increased the data available to astronomers, which lead to the rise of
human computers, famously the
Harvard Computers
The Harvard Computers was a team of women working as skilled workers to process astronomical data at the Harvard Observatory in Cambridge, Massachusetts, United States. The team was directed by Edward Charles Pickering (1877 to 1919) and, follow ...
, to track and analyze the data.
Scientists began discovering forms of light which were invisible to the naked eye:
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s,
gamma ray
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...
s,
radio waves,
microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...
s,
ultraviolet radiation
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
, and
infrared radiation
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
. This had a major impact on astronomy, spawning the fields of
infrared astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in betw ...
,
radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation comin ...
,
x-ray astronomy and finally
gamma-ray astronomy
Gamma-ray astronomy is the astronomical observation of gamma rays,Astronomical literature generally hyphenates "gamma-ray" when used as an adjective, but uses "gamma ray" without a hyphen for the noun. the most energetic form of electromagneti ...
. With the advent of
spectroscopy it was proven that other stars were similar to the Sun, but with a range of
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer.
Thermometers are calibrated in various Conversion of units of temperature, temp ...
s,
mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...
es and sizes.
The science of
stellar spectroscopy
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and othe ...
was pioneered by
Joseph von Fraunhofer and
Angelo Secchi
Angelo Secchi (; 28 June 1818 – 26 February 1878) was an Italian Catholic priest, astronomer from the Italian region of Emilia. He was director of the observatory at the Pontifical Gregorian University (then called the Roman College) for ...
. By comparing the spectra of stars such as
Sirius
Sirius is the brightest star in the night sky. Its name is derived from the Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CM ...
to the Sun, they found differences in the strength and number of their
absorption lines
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identi ...
—the dark lines in stellar spectra caused by the atmosphere's absorption of specific frequencies. In 1865, Secchi began classifying stars into
spectral types. The first evidence of helium was observed on August 18, 1868, as a bright yellow spectral line with a wavelength of 587.49 nanometers in the spectrum of the chromosphere of the Sun. The line was detected by French astronomer Jules Janssen during a total solar eclipse in Guntur, India.
The first direct measurement of the distance to a star (
61 Cygni
61 Cygni is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. Of apparent magnitude 5.20 and 6.05, respectively, they can be seen ...
at 11.4
light-years
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
) was made in 1838 by
Friedrich Bessel
Friedrich Wilhelm Bessel (; 22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method ...
using the
parallax technique. Parallax measurements demonstrated the vast separation of the stars in the heavens. Observation of double stars gained increasing importance during the 19th century. In 1834, Friedrich Bessel observed changes in the proper motion of the star Sirius and inferred a hidden companion.
Edward Pickering discovered the first
spectroscopic binary in 1899 when he observed the periodic splitting of the spectral lines of the star
Mizar
Mizar is a second- magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris ( Latinised as Zeta Ursae Majoris). It forms a well-known naked eye ...
in a 104-day period. Detailed observations of many binary star systems were collected by astronomers such as
Friedrich Georg Wilhelm von Struve
Friedrich Georg Wilhelm von Struve (russian: link=no, Василий Яковлевич Струве, trans. ''Vasily Yakovlevich Struve''; 15 April 1793 – ) was a Baltic German astronomer and geodesist from the famous Struve family. He is be ...
and
S. W. Burnham
Sherburne Wesley Burnham (December 12, 1838 – March 11, 1921) was an American astronomer.
For more than 50 years Burnham spent all his free time observing the heavens, mainly concerning himself with binary stars.
Biography
Sherburne ...
, allowing the masses of stars to be determined from the computation of
orbital elements. The first solution to the problem of deriving an orbit of binary stars from telescope observations was made by Felix Savary in 1827.
In 1847,
Maria Mitchell
Maria Mitchell (Help:IPA/English, /məˈraɪə/; August 1, 1818 – June 28, 1889) was an American astronomer, librarian, naturalist, and educator. In 1847, she discovered a comet named 1847 VI (modern designation C/1847 T1) that was later kno ...
discovered a comet using a telescope.
20th century
With the accumulation of large sets of astronomical data, teams like the
Harvard Computers
The Harvard Computers was a team of women working as skilled workers to process astronomical data at the Harvard Observatory in Cambridge, Massachusetts, United States. The team was directed by Edward Charles Pickering (1877 to 1919) and, follow ...
rose in prominence which lead to many female astronomers, previously relegated as assistants to male astronomers, gaining recognition in the field. The
United States Naval Observatory
United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the Depo ...
(USNO) and other astronomy research institutions hired
human "computers", who performed the tedious calculations while scientists performed research requiring more background knowledge. A number of discoveries in this period were originally noted by the women "computers" and reported to their supervisors.
Henrietta Swan Leavitt
Henrietta Swan Leavitt (; July 4, 1868 – December 12, 1921) was an American astronomer. A graduate of Radcliffe College, she worked at the Harvard College Observatory as a "computer", tasked with examining photographic plates in order to measu ...
discovered the
cepheid variable
A Cepheid variable () is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.
A strong direct relationship between a Cepheid vari ...
star
period-luminosity relation
In astronomy, a period-luminosity relation is a relationship linking the luminosity of pulsating variable stars with their pulsation period.
The best-known relation is the direct proportionality law holding for Classical Cepheid variables, sometim ...
which she further developed into a method of measuring distance outside of the Solar System.
A veteran of the Harvard Computers,
Annie J. Cannon developed the modern version of the stellar classification scheme in during the early 1900s (O B A F G K M, based on color and temperature), manually classifying more stars in a lifetime than anyone else (around 350,000).
The twentieth century saw increasingly rapid advances in the scientific study of stars.
Karl Schwarzschild
Karl Schwarzschild (; 9 October 1873 – 11 May 1916) was a German physicist and astronomer.
Schwarzschild provided the first exact solution to the Einstein field equations of general relativity, for the limited case of a single spherical non-r ...
discovered that the color of a star and, hence, its temperature, could be determined by comparing the
visual magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
against the
photographic magnitude
Photographic magnitude ( or ) is a measure of the relative brightness of a star or other astronomical object as imaged on a photographic film emulsion with a camera attached to a telescope. An object's apparent photographic magnitude depends on i ...
. The development of the
photoelectric
The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, and solid sta ...
photometer
A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ...
allowed precise measurements of magnitude at multiple wavelength intervals. In 1921
Albert A. Michelson
Albert Abraham Michelson FFRS HFRSE (surname pronunciation anglicized as "Michael-son", December 19, 1852 – May 9, 1931) was a German-born American physicist of Polish/Jewish origin, known for his work on measuring the speed of light and esp ...
made the first measurements of a stellar diameter using an
interferometer on the
Hooker telescope
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.
The observat ...
at
Mount Wilson Observatory
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.
The observat ...
.
Important theoretical work on the physical structure of stars occurred during the first decades of the twentieth century. In 1913, the
Hertzsprung-Russell diagram was developed, propelling the astrophysical study of stars.
In
Potsdam
Potsdam () is the capital and, with around 183,000 inhabitants, largest city of the German state of Brandenburg. It is part of the Berlin/Brandenburg Metropolitan Region. Potsdam sits on the River Havel, a tributary of the Elbe, downstream o ...
in 1906, the Danish astronomer
Ejnar Hertzsprung
Ejnar Hertzsprung (; Copenhagen, 8 October 1873 – 21 October 1967, Roskilde) was a Danish chemist and astronomer.
Career
Hertzsprung was born in Frederiksberg, Denmark, the son of Severin and Henriette. He studied chemical engineering at Cop ...
published the first plots of color versus
luminosity for these stars. These plots showed a prominent and continuous sequence of stars, which he named the Main Sequence.
At
Princeton University
Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the ...
,
Henry Norris Russell
Henry Norris Russell ForMemRS HFRSE FRAS (October 25, 1877 – February 18, 1957) was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram (1910). In 1923, working with Frederick Saunders, he d ...
plotted the spectral types of these stars against their absolute magnitude, and found that dwarf stars followed a distinct relationship. This allowed the real brightness of a dwarf star to be predicted with reasonable accuracy.
Successful
models
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...
were developed to explain the interiors of stars and stellar evolution.
Cecilia Payne-Gaposchkin
Cecilia Payne-Gaposchkin (born Cecilia Helena Payne; – ) was a British-born American astronomer and astrophysicist who proposed in her 1925 doctoral thesis that stars were composed primarily of hydrogen and helium. Her groundbreaking conclus ...
first proposed that stars were made primarily of hydrogen and helium in her 1925 doctoral thesis. The spectra of stars were further understood through advances in
quantum physics. This allowed the chemical composition of the stellar atmosphere to be determined.
As evolutionary models of stars were developed during the 1930s,
Bengt Strömgren
Bengt Georg Daniel Strömgren (21 January 1908 – 4 July 1987) was a Danish astronomer and astrophysicist.
Life and career
Bengt Strömgren was born in Gothenburg. His parents were Hedvig Strömgren (née Lidforss) and Elis Strömgren, wh ...
introduced the term Hertzsprung–Russell diagram to denote a luminosity-spectral class diagram.
A refined scheme for
stellar classification was published in 1943 by
William Wilson Morgan
William Wilson Morgan (January 3, 1906 – June 21, 1994) was an American astronomer and astrophysicist. The principal theme in Morgan's work was stellar and galaxy classification. He is also known for helping prove the existence of spiral arms i ...
and
Philip Childs Keenan
Philip Childs Keenan (March 31, 1908 – April 20, 2000) was an American astronomer.
Keenan was an American spectroscopist who collaborated with William Wilson Morgan and Edith Kellman (1911–2007) to develop the MKK stellar spectral classi ...
.
The existence of our
galaxy, the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
, as a separate group of stars was only proven in the 20th century, along with the existence of "external" galaxies, and soon after, the expansion of the
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. ...
seen in the recession of most galaxies from us. The "
Great Debate" between
Harlow Shapley
Harlow Shapley (November 2, 1885 – October 20, 1972) was an American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal.
Shapley used Cepheid variable stars to estim ...
and
Heber Curtis
Heber Doust Curtis (June 27, 1872 – January 9, 1942) was an American astronomer. He participated in 11 expeditions for the study of solar eclipses, and, as an advocate and theorist that additional galaxies existed outside of the Milky Way, wa ...
, in the 1920s, concerned the nature of the Milky Way, spiral nebulae, and the dimensions of the universe.
With the advent of
quantum physics,
spectroscopy was further refined.
The Sun was found to be part of a
galaxy made up of more than 10
10 stars (10 billion stars). The existence of other galaxies, one of the matters of ''
the great debate'', was settled by
Edwin Hubble, who identified the
Andromeda nebula as a different galaxy, and many others at large distances and receding, moving away from our galaxy.
Physical cosmology
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of f ...
, a discipline that has a large intersection with astronomy, made huge advances during the 20th century, with the model of the hot
Big Bang heavily supported by the evidence provided by astronomy and physics, such as the
redshifts of very distant galaxies and radio sources, the
cosmic microwave background radiation
In Big Bang cosmology the cosmic microwave background (CMB, CMBR) is electromagnetic radiation that is a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all space ...
,
Hubble's law
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving a ...
and
cosmological abundances of elements.
See also
*
Age of the universe
In physical cosmology, the age of the universe is the time elapsed since the Big Bang. Astronomers have derived two different measurements of the age of the universe:
a measurement based on direct observations of an early state of the universe, ...
*
Anthropic principle
*
Archaeoastronomy
Archaeoastronomy (also spelled archeoastronomy) is the interdisciplinary or multidisciplinary study of how people in the past "have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cul ...
*
Astrotheology
Astrotheology, astral mysticism, astral religion, astral or stellar theology (also referred to as astral or star worship) is the worship of the stars (individually or together as the night sky), the planets, and other heavenly bodies as deities, ...
*
Big Bang
*
Cosmology
Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...
*
Expansion of the universe
*
Hebrew astronomy Hebrew astronomy refers to any astronomy written in Hebrew or by Hebrew speakers, or translated into Hebrew, or written by Jews in Judeo-Arabic. It includes a range of genres from the earliest astronomy and cosmology contained in the Bible, mainly ...
*
History of astrology
Astrological beliefs in correspondences between celestial observations and terrestrial events have influenced various aspects of human history, including world-views, language and many elements of social culture.
Among West Eurasian peoples, th ...
*
History of Mars observation
The history of Mars observation is about the recorded history of observation of the planet Mars. Some of the early records of Mars' observation date back to the era of the ancient Egyptian astronomers in the 2nd millennium BCE. Chinese records a ...
*
History of supernova observation
The known history of supernova observation goes back to 185 AD, when supernova SN 185 appeared; which is the oldest appearance of a supernova recorded by mankind. Several additional supernovae within the Milky Way galaxy have been recorded since t ...
*
History of the telescope
The history of the telescope can be traced to before the invention of the earliest known telescope, which appeared in 1608 in the Netherlands, when a patent was submitted by Hans Lippershey, an eyeglass maker. Although Lippershey did not rec ...
* ''
Letters on Sunspots
'' Letters on Sunspots '' (''Istoria e Dimostrazioni intorno alle Macchie Solari'') was a pamphlet written by Galileo Galilei in 1612 and published in Rome by the Accademia dei Lincei in 1613. In it, Galileo outlined his recent observation of dar ...
''
*
List of astronomers
The following is a list of astronomers, astrophysicists and other notable people who have made contributions to the field of astronomy. They may have won major prizes or awards, developed or invented widely used techniques or technologies within as ...
*
List of astronomical instrument makers
The following is a list of astronomical instrument makers, along with lifespan and country of work, if available.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V ...
*
List of astronomical observatories
This is a list of astronomical observatories ordered by name, along with initial dates of operation (where an accurate date is available) and location. The list also includes a final year of operation for many observatories that are no longer in ...
*
List of French astronomers
The following are list of French astronomers, astrophysicists and other notable French people who have made contributions to the field of astronomy. They may have won major prizes or awards, developed or invented widely used techniques or technolo ...
*
List of Hungarian astronomers
*
List of Russian astronomers and astrophysicists
This list of Russian astronomers and astrophysicists includes the famous astronomers, astrophysicists and cosmologists from the Russian Empire, the Soviet Union and the Russian Federation.
Alphabetical list
__NOTOC__
A
* Tateos Agekian, one ...
*
List of Slovenian astronomers
*
List of women astronomers
The following is a list of astronomers, astrophysicists and other notable women who have made contributions to the field of astronomy.
__NOTOC__
A
* Madge Adam (1912–2001), English solar astronomer
* Maggie Aderin-Pocock (born 1968), Engli ...
*
Patronage in astronomy image:Johannes-kepler-tabulae-rudolphinae-google-arts-culture.jpg, Book frontispiece, Frontispiece of the Rudolphine Tables
Patronage in astronomy is an approach which one can use to examine the history of astronomy from a cultural standpoint. Rath ...
*
Physical cosmology
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of f ...
*
Timeline of astronomy
__NOTOC__
750 BCE
Mayan astronomers discover an 18.7-year cycle in the rising and setting of the Moon. From this they created the first almanacs – tables of the movements of the Sun, Moon, and planets for the use in astrology. In 6th ce ...
*
Timeline of Solar System astronomy
The following is a timeline of Solar System astronomy and science. It includes the advances in the knowledge of the Earth at Planetary science, planetary scale, as part of it.
Direct observation
Humans (''Homo sapiens'') have inhabited the Earth ...
Notes
Historians of astronomy
* Scholars Past
Willy Hartner Otto Neugebauer
Otto Eduard Neugebauer (May 26, 1899 – February 19, 1990) was an Austrian-American mathematician and historian of science who became known for his research on the history of astronomy and the other exact sciences as they were practiced in anti ...
,
B. L. van der Waerden
Bartel Leendert van der Waerden (; 2 February 1903 – 12 January 1996) was a Dutch mathematician and historian of mathematics.
Biography
Education and early career
Van der Waerden learned advanced mathematics at the University of Amsterd ...
* Scholars Present
Stephen G. BrushStephen J. Dick Owen Gingerich
Owen Jay Gingerich (; born 1930) is professor emeritus of astronomy and of the history of science at Harvard University and a senior astronomer emeritus at the Smithsonian Astrophysical Observatory. In addition to his research and teaching, he has ...
Bruce StephensonCurtis A. Wilson* Astronomer-historians.
J. B. J. Delambre,
J. L. E. Dreyer,
Donald Osterbrock,
Carl Sagan,
F. Richard Stephenson
F. Richard Stephenson (born Francis Richard Stephenson, 26 April 1941) is an Emeritus Professor at the Durham University, University of Durham, in the Physics department and the East Asian Studies department. His research concentrates on Histo ...
References
*
Aaboe, Asger. ''Episodes from the Early History of Astronomy''. Springer-Verlag 2001
* Aveni, Anthony F. ''Skywatchers of Ancient Mexico''. University of Texas Press 1980
* Berry, Arthur (1898
A Brief History of Astronomyvia
Internet Archive
The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...
*
Dreyer, J. L. E. ''History of Astronomy from Thales to Kepler'', 2nd edition. Dover Publications 1953 (revised reprint of ''History of the Planetary Systems from Thales to Kepler'', 1906)
* Eastwood, Bruce. ''The Revival of Planetary Astronomy in Carolingian and Post-Carolingian Europe'', Variorum Collected Studies Series CS 279 Ashgate 2002
* .
* Antoine Gautier, ''L'âge d'or de l'astronomie ottomane'', in L'Astronomie, (Monthly magazine created by
Camille Flammarion
Nicolas Camille Flammarion FRAS (; 26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fic ...
in 1882), December 2005, volume 119.
* Hodson, F. R. (ed.). ''The Place of Astronomy in the Ancient World'': A Joint Symposium of the Royal Society and the British Academy. Oxford University Press, 1974
* Hoskin, Michael. ''The History of Astronomy: A Very Short Introduction''. Oxford University Press.
*
*
Pannekoek, Anton (1989) ''A History of Astronomy'', Dover Publications
*
Pedersen, Olaf (1993) ''Early Physics and Astronomy: A Historical Introduction'', revised edition. Cambridge University Press
* .
* .
* Stephenson, Bruce. ''Kepler's Physical Astronomy'', Studies in the History of Mathematics and Physical Sciences, 13. New York: Springer, 1987
* Walker, Christopher (ed.). ''Astronomy before the telescope''. British Museum Press 1996
Further reading
*
*
UNESCO Medieval astronomy in Europe*Magli, Giulio. "On the possible discovery of precessional effects in ancient astronomy." arXiv preprint physics/0407108 (2004).
Refereed Journals
DIO: ''The International Journal of Scientific History''* ''
Journal for the History of Astronomy
''Journal for the History of Astronomy'' (''JHA'') is a peer-reviewed academic journal that publishes papers in the History of Astronomy from earliest times to the present, and in history in the service of astronomy. The journal's founding editor ...
''
''Journal of Astronomical History and Heritage''
External links
*
Paris Observatory books and manuscriptsUNESCO-IAU Portal to the Heritage of AstronomyAstronomiae Historia / History of Astronomyat the Astronomical Institutes of Bonn University.
Society for the History of Astronomy Ancient Astronomy and Astrology at
LacusCurtius
LacusCurtius is a website specializing in ancient Rome, currently hosted on a server at the University of Chicago. It went online on August 26, 1997; in July 2021 it had "3707 webpages, 765 photos, 772 drawings & engravings, 120 plans, 139 maps." T ...
Mesoamerican Archaeoastronomy''The Book of Instruction on Deviant Planes and Simple Planes''is a manuscript in Arabic that dates back to 1740 and talks about practical astronomy, with diagrams.
Astronomy & Empire BBC Radio 4 discussion with Simon Schaffer, Kristen Lippincott & Allan Chapman (''In Our Time'', May 4, 2006)
"Sharing the sky: astronomers and astrologers in the West" an exhibition of the Library of the Observatory of Paris about the shared history of astronomy and astrology around the Mediterranea.
{{DEFAULTSORT:History Of Astronomy
Astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
Astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...