Astronomy is the oldest of the natural sciences, dating back to
antiquity, with its origins in the religious, mythological,
cosmological, calendrical, and astrological beliefs and practices of
prehistory: vestiges of these are still found in astrology, a
discipline long interwoven with public and governmental astronomy, and
not completely disentangled from it until a few centuries ago in the
Western World (see astrology and astronomy). In some cultures,
astronomical data was used for astrological prognostication.
Ancient astronomers were able to differentiate between stars and
planets, as stars remain relatively fixed over the centuries while
planets will move an appreciable amount during a comparatively short
1 Early history
2 Prehistoric Europe
3 Ancient times
3.3 Greece and
4 Medieval Middle East
5 Medieval Western Europe
7 Uniting physics and astronomy
8 Completing the solar system
9 Modern astronomy
Cosmology and the expansion of the universe
11 New windows into the Cosmos open
12 See also
14 Historians of astronomy
16 Further reading
17 Refereed Journals
18 External links
Early cultures identified celestial objects with gods and spirits.
They related these objects (and their movements) to phenomena such as
rain, drought, seasons, and tides. It is generally believed that the
first astronomers were priests, and that they understood celestial
objects and events to be manifestations of the divine, hence early
astronomy's connection to what is now called astrology. Ancient
structures with possibly astronomical alignments (such as Stonehenge)
probably fulfilled astronomical, religious, and social functions.
Calendars of the world have often been set by observations of the Sun
Moon (marking the day, month and year), 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.
sunset at the equinox from the prehistoric site of Pizzo Vento at
Fondachelli Fantina, Sicily
The common modern calendar is based on the Roman calendar. Although
originally a lunar calendar, 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
Julius Caesar instigated calendar reform in
BCE and introduced what is now called the Julian calendar,
based upon the 365 1⁄4 day year length originally proposed by
the 4th century
BCE Greek astronomer Callippus.
Main article: Archaeoastronomy
Nebra sky disk
Nebra sky disk
Germany 1600 BC
Calendrical functions of the
Berlin Gold Hat
Berlin Gold Hat c. 1000 BC
Since 1990 our understanding of prehistoric Europeans has been
radically changed by discoveries of ancient astronomical artifacts
throughout Europe. The artifacts demonstrate that Neolithic and Bronze
Age Europeans had a sophisticated knowledge of mathematics and
Among the discoveries are:
Bone sticks from locations like Africa and
Europe from possibly as
long ago as 35,000
BCE are marked in ways that tracked the moon's
Warren Field calendar in the Dee River valley of Scotland's
Aberdeenshire. First excavated in 2004 but only in 2013 revealed as a
find of huge significance, it is to date the world´s 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 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, Germany, and the
Czech Republic during a
200-year period starting shortly after 5000 BC.
The Nebra sky disc is a
Bronze Age 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 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). 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
Kokino site, discovered in 2001, sits atop an extinct volcanic
cone at an elevation of 1,013 metres (3,323 ft), occupying about
0.5 hectares overlooking the surrounding countryside in Macedonia. A
Bronze Age 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 lunations 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 hats of Germany,
Switzerland dating from 1400-800 BC
are associated with the
Bronze Age Urnfield culture. The Golden hats
are decorated with a spiral motif of the
Sun and the Moon. They were
probably a kind of calendar used to calibrate between the lunar and
solar calendars. Modern scholarship has demonstrated that the
ornamentation of the gold leaf cones of the Schifferstadt type, to
Berlin Gold Hat
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
calendar. The object would have permitted the determination of dates
or periods in both lunar and solar calendars.
Main article: Mesopotamian astronomy
Babylonian astrology and Babylonian calendar
Babylonian tablet recording
Halley's comet in 164 BC.
The origins of Western astronomy can be found in Mesopotamia, the
"land between the rivers"
Tigris and Euphrates, where the ancient
kingdoms of Sumer, Assyria, and
Babylonia were located. A form of
writing known as cuneiform 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, which gave
planetary gods an important role in
Mesopotamian mythology and
religion, began with the Sumerians. They also used a sexagesimal (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, of 60 minutes each, began with the Sumerians.
For more information, see the articles on
Babylonian numerals and
Classical sources frequently use the term Chaldeans for the
astronomers of Mesopotamia, who were, in reality, priest-scribes
specializing in astrology 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 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 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, which lists the first and last visible risings
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, 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, 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
A significant increase in the quality and frequency of Babylonian
observations appeared during the reign of
Nabonassar (747–733 BC).
The systematic records of ominous phenomena in Babylonian astronomical
diaries that began at this time allowed for the discovery of a
repeating 18-year cycle of lunar eclipses, for example. The Greek
Ptolemy 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, who was
a supporter of the heliocentric model.
Babylonian astronomy was the basis for much of what was done in Greek
Hellenistic astronomy, in classical Indian astronomy, in Sassanian
Iran, in Byzantium, in Syria, in Islamic astronomy, in Central Asia,
and in Western Europe.
Historical Jantar Mantar observatory in Jaipur, India.
Main article: Indian astronomy
Further information: Jyotisha
Astronomy in the Indian subcontinent dates back to the period of Indus
Valley Civilization 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, dating from the Vedic period. Vedanga
Jyotisha describes rules for tracking the motions of the
Sun and the
Moon for the purposes of ritual. During the 6th century, astronomy was
influenced by the Greek and Byzantine astronomical traditions.
Aryabhata (476–550), in his magnum opus
propounded a computational system based on a planetary model in which
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 eclipses, and the instantaneous motion of the
Moon.[page needed] Early followers of Aryabhata's model
included Varahamihira, Brahmagupta, and Bhaskara II.
Astronomy was advanced during the
Shunga Empire and many star
catalogues were produced during this time. The Shunga period is
known[according to whom?] 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
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
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
Nilakantha Somayaji and Jyeshtadeva, who were members of
Kerala school of astronomy and mathematics 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,
Saturn orbit the Sun, which in turn orbits
the Earth, similar to the
Tychonic system later proposed by Tycho
Brahe 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 motion of Mercury and Venus. Most astronomers of the
Kerala school of astronomy and mathematics who followed him accepted
his planetary model.
Main article: Greek astronomy
Antikythera Mechanism was an analog computer from 150–100 BC
designed to calculate the positions of astronomical objects.
Ancient Greeks 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
Callippus of Cyzicus. Their models were based on nested
homocentric spheres centered upon the Earth. Their younger
Heraclides Ponticus proposed that the
around its axis.
A different approach to celestial phenomena was taken by natural
philosophers such as
Plato and Aristotle. 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
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, 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
Aristarchus of Samos was the first to suggest a
heliocentric system, although only fragmentary descriptions of his
idea survive. Eratosthenes, using the angles of shadows created at
widely separated regions, estimated the circumference of the Earth
with great accuracy.
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 which
in turn carried around a planet. The first such model is attributed to
Apollonius of Perga
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 and
the compilation of the first star catalog in which he proposed our
modern system of apparent magnitudes.
Antikythera mechanism, an ancient Greek 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, between
Kythera and Crete. The
device became famous for its use of a differential gear, 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
Greek astronomy is seen with
Ptolemy of Alexandria, 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. 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
Aristarchus of Samos
Aristarchus of Samos four centuries earlier.
Main article: Egyptian astronomy
Chart from Senemut's tomb, 18th dynasty
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, which, because of the
precession of the equinoxes, was at that time Thuban, a faint star in
the constellation of Draco. Evaluation of the site of the temple
Amun-Re at Karnak, taking into account the change over time of the
obliquity of the ecliptic, has shown that the Great Temple was aligned
on the rising of the midwinter sun. The length of the corridor
down which sunlight would travel would have limited illumination at
other times of the year.
Astronomy played a considerable part in religious matters for fixing
the dates of festivals and determining the hours of the night. The
titles of several temple books are preserved recording the movements
and phases of the sun, moon and stars. The rising of
Sopdet, Greek: Sothis) at the beginning of the inundation was a
particularly important point to fix in the yearly calendar.
Writing in the Roman era,
Clement of Alexandria
Clement of Alexandria 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. He must know by heart the
Hermetic 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
The Astrologer's instruments (horologium and palm) are a plumb line
and sighting instrument[clarification needed]. 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 arms length. The "Hermetic"
books which Clement refers to are the Egyptian theological texts,
which probably have nothing to do with
From the tables of stars on the ceiling of the tombs of
Rameses VI and
Rameses IX 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 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 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.
Printed star map of
Su Song (1020–1101) showing the south polar
Main article: Chinese astronomy
Book of Silk, Chinese astrology, and Timeline of Chinese
The astronomy of
East Asia began in China.
Solar term was completed in
Warring States period. The knowledge of
Chinese astronomy was
introduced into East Asia.
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
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" which suddenly appeared
among the fixed stars. 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, a Chinese
astronomer, in the 4th century BC.
"El Caracol" observatory temple at Chichen Itza, Mexico.
Maya calendar and Aztec calendar
Maya astronomical codices include detailed tables for calculating
phases of the Moon, the recurrence of eclipses, and the appearance and
Venus as morning and evening star. The Maya based
their calendrics in the carefully calculated cycles of the Pleiades,
the Sun, the Moon, Venus, Jupiter, Saturn, Mars, and also they had a
precise description of the eclipses as depicted in the Dresden Codex,
as well as the ecliptic or zodiac, and the
Milky Way 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
Mars is also mentioned in preserved astronomical codices
and early mythology.
Maya calendar was not tied to the Sun, John Teeple has
proposed that the Maya calculated the solar year to somewhat greater
accuracy than the Gregorian calendar. Both astronomy and an
intricate numerological scheme for the measurement of time were
vitally important components of Maya religion.
Medieval Middle East
Astronomy in medieval Islam
See also: Maragheh observatory, Ulugh Beg Observatory, and Istanbul
observatory of Taqi al-Din
Arabic astrolabe from 1208 AD
The Arabic and the Persian world under
Islam had become highly
cultured, and many important works of knowledge from Greek astronomy
Indian astronomy 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. This led to the emergence of the first
astronomical observatories in the
Muslim world by the early 9th
Zij star catalogues were produced at these
In the 10th century,
Abd al-Rahman al-Sufi
Abd al-Rahman al-Sufi (Azophi) carried out
observations on the stars and described their positions, magnitudes,
brightness, and colour and drawings for each constellation in his Book
of Fixed Stars. He also gave the first descriptions and pictures of "A
Little Cloud" now known as the Andromeda Galaxy. 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 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,
Iran, by the astronomer
Abu-Mahmud al-Khujandi who observed a series
of meridian 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
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 laws as Earth, the first
elaborate experiments related to astronomical phenomena, the
introduction of exacting empirical observations and experimental
techniques, and the introduction of empirical testing by Ibn
al-Shatir, who produced the first model of lunar motion which matched
Natural philosophy (particularly Aristotelian physics) was separated
from astronomy by
Ibn al-Haytham (Alhazen) in the 11th century, by Ibn
al-Shatir in the 14th century, and Qushji in the 15th century,
leading to the development of an astronomical physics.
Medieval Western Europe
Further information: Science in the Middle Ages
9th century diagram of the positions of the seven planets on 18 March
After the significant contributions of Greek scholars to the
development of astronomy, it entered a relatively static era in
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
Europe entered the Middle Ages with great difficulties that
affected the continent's intellectual production. The advanced
astronomical treatises of classical antiquity were written in Greek,
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
Macrobius, Pliny, Martianus Capella, and Calcidius. In the 6th
Gregory of Tours
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 of Jarrow published an
influential text, On the Reckoning of Time, providing churchmen with
the practical astronomical knowledge needed to compute the proper date
Easter 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 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. 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
Gerbert of Aurillac 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
Hermann of Reichenau were writing texts in
Latin on the uses and
construction of the astrolabe and others, such as Walcher of Malvern,
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
seek out more advanced astronomical and astrological texts, which they
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 wrote a series of
influential introductory astronomy textbooks: the Sphere, a Computus,
a text on the Quadrant, and another on Calculation.
In the 14th century, Nicole Oresme, 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
Nicholas of Cusa
Nicholas of Cusa suggested in some of his scientific
writings that the
Earth revolved around the Sun, and that each star is
itself a distant sun. He was not, however, describing a scientifically
verifiable theory of the universe.
Galileo Galilei (1564–1642) crafted his own telescope and discovered
Moon had craters, that
Jupiter had moons, that the
spots, and that
Venus had phases like our Moon.
Astronomia nova and Epitome Astronomiae Copernicanae
The renaissance came to astronomy with the work of Nicolaus
Copernicus, who proposed a heliocentric system, in which the planets
revolved around the
Sun and not the Earth. His De revolutionibus
provided a full mathematical discussion of his system, using the
geometrical techniques that had been traditional in astronomy since
before the time of Ptolemy. His work was later defended, expanded upon
and modified by
Galileo Galilei and Johannes Kepler.
Galileo was considered the father of observational astronomy. He was
among the first to use a telescope to observe the sky and after
constructing a 20x refractor telescope he discovered the four largest
Jupiter in 1610. This was the first observation of satellites
orbiting another planet. He also found that our
Moon had craters and
observed (and correctly explained) sunspots. Galileo noted that Venus
exhibited a full set of phases resembling lunar phases. Galileo argued
that these observations supported the Copernican system and were, to
some extent, incompatible with the favored model of the
Earth at the
center of the universe. He may have even observed the planet
Neptune in 1612 and 1613, over 200 years before it was discovered, but
it is unclear if he was aware of what he was looking at. However, he
faced much opposition from the Catholic Church as this "heliocentric
theory" went directly against geocentric system that had been
referenced in the Bible. He was eventually tried and pled guilty to a
"strong suspicion of heresy" which was a lighter sentence then what
was proportional during the time. Although this came at some expense:
his book was banned, he spent one day in prison, and he was put under
house arrest until he died in 1642. 
Uniting physics and astronomy
Plate with figures illustrating articles on astronomy, from the 1728
Although the motions of celestial bodies had been qualitatively
explained in physical terms since
Aristotle introduced celestial
movers in his Metaphysics and a fifth element in his On the Heavens,
Johannes Kepler was the first to attempt to derive mathematical
predictions of celestial motions from assumed physical causes.
Combining his physical insights with the unprecedentedly accurate
naked-eye observations made by Tycho Brahe, Kepler
discovered the three laws of planetary motion that now carry his
Isaac Newton developed further ties between physics and astronomy
through his law of universal gravitation. Realising that the same
force that attracted 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
Philosophiae Naturalis Principia Mathematica, he derived Kepler's laws
from first principles. 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 and Cassini accepted only parts of Newton's system,
preferring their own philosophies. It wasn't until
a popular account in 1738 that the tide changed. In 1748, the
French Academy of Sciences
French Academy of Sciences offered a reward for solving the
Saturn which was eventually solved by
Euler and Lagrange.
Laplace completed the theory of the planets
towards the end of the century.
Edmund Halley succeeded Flamsteed as
Astronomer Royal in England and
succeeded in predicting the return in 1758 of the comet that bears his
Sir William Herschel
Sir William Herschel found the first new planet, Uranus, to be
observed in modern times in 1781. The gap between the planets
Jupiter disclosed by the
Titius–Bode law was filled by the discovery
of the asteroids Ceres and Pallas in 1801 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 as early as 1659.
Mars surface map of Giovanni Schiaparelli.
Astronomy and Observational astronomy
In the 19th century it was discovered that, when sunlight was
dispersed, a multitude of spectral lines were observed (regions where
there was less or no light). Experiments with hot gases showed that
the same lines could be observed in the spectra of gases, specific
lines corresponding to unique elements. It was proved that the
chemical elements found in the
Sun (chiefly hydrogen and helium) were
also found on Earth. During the 20th century spectroscopy (the study
of these lines) advanced, especially because of the advent of quantum
physics, that was necessary to understand the observations.
Although in previous centuries noted astronomers were exclusively
male, at the turn of the 20th century women began to play a role in
the great discoveries. In this period prior to modern computers, women
at the United States Naval
Observatory (USNO), Harvard University, and
other astronomy research institutions began to be hired as 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. For example, at the
Henrietta Swan Leavitt
Henrietta Swan Leavitt discovered the cepheid
variable star period-luminosity relation which she further developed
into a method of measuring distance outside of our solar system. Annie
Jump Cannon, also at Harvard, organized the stellar spectral types
according to stellar temperature. In 1847,
Maria Mitchell discovered a
comet using a telescope. According to Lewis D. Eigen, Cannon alone,
"in only 4 years discovered and catalogued more stars than all the men
in history put together." Most of these women received little or
no recognition during their lives due to their lower professional
standing in the field of astronomy. Although their discoveries and
methods are taught in classrooms around the world, few students of
astronomy can attribute the works to their authors or have any idea
that there were active female astronomers at the end of the 19th
Cosmology and the expansion of the universe
CMB (Cosmic microwave background) results from
WMAP and Planck documenting a progress in 1989-2013.
Physical cosmology § History of study
Most of our current knowledge was gained during the 20th century. With
the help of the use of photography, fainter objects were observed. Our
sun was found to be part of a galaxy made up of more than 1010 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, 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, Hubble's
law and cosmological abundances of elements.
New windows into the Cosmos open
Hubble Space Telescope.
In the 19th century, scientists began discovering forms of light which
were invisible to the naked eye: X-Rays, gamma rays, radio waves,
microwaves, ultraviolet radiation, and infrared radiation. This had a
major impact on astronomy, spawning the fields of infrared astronomy,
radio astronomy, x-ray astronomy and finally gamma-ray astronomy. With
the advent of spectroscopy it was proven that other stars were similar
to our own sun, but with a range of temperatures, masses and sizes.
The existence of our galaxy, the Milky Way, 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
seen in the recession of most galaxies from us.
X-ray astronomy portal
Age of the universe
History of astrology
History of supernova observation
History of telescopes
Letters on Sunspots
Metric expansion of space
Patronage in Astronomy
Timeline of astronomy
List of astronomical instrument makers
List of astronomers
List of Russian astronomers and astrophysicists
List of astronomical observatories
^ Krupp, Edwin C. (2003), Echoes of the Ancient Skies: The Astronomy
of Lost Civilizations,
Astronomy Series, Courier Dover Publications,
pp. 62–72, ISBN 0-486-42882-6, retrieved 2011-04-12
^ Nilsson, Martin P. (1920), Primitive Time-Reckoning. A Study in the
Origins and Development of the Art of Counting Time among the
Primitive and Early
Culture Peoples, Skrifter utgivna av Humanistiska
Vetenskapssamfundet i Lund, 1, Lund: C. W. K. Gleerup,
^ Marshak, Alexander. 1972, The Roots of Civilization
^ "The Beginning of Time?". University of Birmingham. 2013.
^ "'World's oldest calendar' discovered in Scottish field". BBC News.
^ "World's Oldest
Calendar Discovered in U.K." Roff Smith, National
Geographic. July 15, 2013.
^ V. Gaffney; et al. (2013), "Time and a Place: A luni-solar
'time-reckoner' from 8th millennium BC Scotland", Internet Archaeology
(34), doi:10.11141/ia.34.1, retrieved 7 Oct 2014
^ "Sonnenobservatorium Goseck". Sonnenobservatorium Goseck.
^ The Nebra Sky Disc, Landesamt für Denkmalpflege und Archäologie
Sachsen-Anhalt / Landesmuseum für Vorgeschichte, retrieved 15 October
^ Nebra Sky Disc, UNESCO: Memory of the World, retrieved 15 October
^ The Sky Disc of Nebra:
Bronze Age Sky Disc Deciphered, Deutsche
Welle, 2002, retrieved 15 October 2014
^ "Archaeo-astronomical Site Kokino", UNESCO World Heritage, 2009,
retrieved 27 October 2014
Europe Before Rome: A Site-by-Site Tour of the Stone, Bronze, and
Iron Ages". T. Douglas Price, Oxford University Press. 2013.
^ "The Mayan and Other Ancient Calendars". Geoff Stray, Bloomsbury
Publishing USA. 2007. p. 14.
^ Wilfried Menghin (Hrsg.): Acta Praehistorica et Archaeologica. Unze,
Potsdam 32.2000, S. 31-108. ISSN 0341-1184
^ Pingree (1998)
^ Pingree (1998)
^ a b Pierre-Yves Bely; Carol Christian; Jean-René Roy. A Question
and Answer Guide to Astronomy. Cambridge University Press.
^ Subbarayappa, B. V. (14 September 1989). "Indian astronomy: An
historical perspective". In Biswas, S. K.; Mallik, D. C. V.;
Vishveshwara, C. V. Cosmic Perspectives. Cambridge University Press.
pp. 25–40. ISBN 978-0-521-34354-1.
^ Neugebauer, O. (1952) Tamil Astronomy: A Study in the History of
Astronomy in India. Osiris, 10:252-276.
^ Joseph (2000).
^ Thurston, H, Early Astronomy. Springer, 1994, p. 178–188.
^ Kelley, David H.; Milone, Eugene F. (2011). Exploring Ancient Skies:
A Survey of Ancient and Cultural Astronomy. p. 293.
^ George G. Joseph (2000), The Crest of the Peacock: Non-European
Roots of Mathematics, 2nd edition, p. 408, Penguin Books, London,
^ Ramasubramanian, K.; Srinivas, M. D.; Sriram, M. S. (1994).
"Modification of the earlier Indian planetary theory by the Kerala
astronomers (c. 1500 AD) and the implied heliocentric picture of
planetary motion". Current Science. 66: 784–790.
^ Plato, Timaeus, 33B-36D
^ Aristotle, Metaphysics, 1072a18-1074a32
^ Pedersen, Early Physics and Astronomy, pp. 55–6
^ Pedersen, Early Physics and Astronomy, pp. 45–7
^ Full version at Met Museum
^ Ruggles, C.L.N. (2005), Ancient Astronomy, pages 354–355.
ABC-Clio. ISBN 1-85109-477-6.
^ Krupp, E.C. (1988). "Light in the Temples", in C.L.N. Ruggles:
Records in Stone: Papers in Memory of Alexander Thom. CUP, 473–499.
^ Clement of Alexandria, Stromata, vi. 4
^ Neugebauer O, Egyptian Planetary Texts, Transactions, American
Philosophical Society, Vol. 32, Part 2, 1942, Page 237.
Astronomy Archived 2007-06-06 at the Wayback Machine.
^ A. F. Aveni, Skywatchers of Ancient Mexico, (Austin: Univ. of Texas
Pr., 1980), pp. 173–99.
^ A. F. Aveni, Skywatchers of Ancient Mexico, (Austin: Univ. of Texas
Pr, 1980), pp. 170–3.
^ Ute Ballay (November 1990), "The Astronomical Manuscripts of
Naṣīr al-Dīn Ṭūsī", Arabica, Brill Publishers, 37 (3):
389–392 , doi:10.1163/157005890X00050, JSTOR 4057148
^ Micheau, Francoise, The Scientific Institutions in the Medieval Near
East, pp. 992–3 , in Roshdi Rashed & Régis Morelon
(1996), Encyclopedia of the History of Arabic Science, pp. 985–1007,
Routledge, London and New York.
^ Nas, Peter J (1993), Urban Symbolism, Brill Academic Publishers,
p. 350, ISBN 90-04-09855-0
^ Kepple, George Robert; Sanner, Glen W. (1998), The
Observer's Guide, Volume 1, Willmann-Bell, Inc., p. 18,
^ "Observatoire de Paris (Abd-al-Rahman Al Sufi)". Retrieved
^ "Observatoire de Paris (LMC)". Retrieved 2007-04-19.
^ Al-Khujandi, Abu Ma?mud ?amid Ibn Al-Khi?r, Complete Dictionary
of Scientific Biography, 2008
^ O'Connor, John J.; Robertson, Edmund F., "Abu Mahmud Hamid ibn
al-Khidr Al-Khujandi", MacTutor History of
University of St Andrews .
^ Krebs, Robert E. (2004), Groundbreaking Scientific Experiments,
Inventions, and Discoveries of the Middle Ages and the Renaissance,
Greenwood Press, p. 196, ISBN 0-313-32433-6
^ Saliba, George (1994). "Early Arabic Critique of Ptolemaic
Cosmology: A Ninth-Century Text on the Motion of the Celestial
Spheres". Journal for the History of Astronomy. 25: 115–141 .
^ Toby Huff, The Rise of Early Modern Science, p. 326. Cambridge
University Press, ISBN 0-521-52994-8.
^ Faruqi, Y. M. (2006). "Contributions of Islamic scholars to the
scientific enterprise". International Education Journal. 7 (4):
^ Roshdi Rashed (2007). "The Celestial Kinematics of Ibn al-Haytham",
Arabic Sciences and Philosophy 17, p. 7-55. Cambridge University
^ F. Jamil Ragep (2001), "Tusi and Copernicus: The Earth's Motion in
Context", Science in Context 14 (1-2), p. 145–163. Cambridge
^ Henry Smith Williams, The Great Astronomers (New York: Simon and
Schuster, 1930), pp. 99–102 describes "the record of astronomical
progress" from the Council of Nicea (325 AD) to the time of Copernicus
(1543 AD) on four blank pages.
^ Stephen C. McCluskey, Astronomies and Cultures in Early Medieval
Europe, (Cambridge: Cambridge University Press, 1999)
^ Bruce S. Eastwood, Ordering the Heavens: Roman
Cosmology in the Carolingian Renaissance, (Leiden: Brill, 2007)
^ Stephen C. McCluskey, Astronomies and Cultures in Early Medieval
Europe, (Cambridge: Cambridge University Press, 1999), pp. 101–110
^ Faith Wallis, ed. and trans, Bede: The Reckoning of Time,
(Liverpool: Liverpool University Press, 2004), pp. xviii-xxxiv
^ Stephen C. McCluskey, Astronomies and Cultures in Early Medieval
Europe, (Cambridge: Cambridge University Press, 1999), pp. 131–164
^ David Juste, "Neither Observation nor Astronomical Tables: An
Alternative Way of Computing the Planetary Longitudes in the Early
Western Middle Ages," pp. 181–222 in Charles Burnett, Jan P.
Hogendijk, Kim Plofker, and Michio Yano, Studies in the Exact Sciences
in Honour of David Pingree, (Leiden: Brill, 2004)
^ Stephen C. McCluskey, Astronomies and Cultures in Early Medieval
Europe, (Cambridge: Cambridge University Press, 1999), pp. 171–187
^ Stephen C. McCluskey, Astronomies and Cultures in Early Medieval
Europe, (Cambridge: Cambridge University Press, 1999), pp. 188–192
^ Pedersen, Olaf (1985). "In Quest of Sacrobosco". Journal for the
History of Astronomy. 16: 175–221.
^ Nicole Oresme, Le Livre du ciel et du monde, xxv, ed. A. D. Menut
and A. J. Denomy, trans. A. D. Menut, (Madison: Univ. of Wisconsin
Pr., 1968), quotation at pp. 536–7.
^ Galileo Galilei: The Invention of the Telescope and the Foundation
of Modern Astronomy
^ Hirschfeld, Alan (2001). Parallax: The Race to Measure the Cosmos.
New York, New York: Henry Holt. ISBN 978-0-8050-7133-7.
^ Britt, Robert Roy (2009). "Galileo discovered Neptune, new theory
claims". MSNBC News. Retrieved 10 July 2009.
^ Bruce Stephenson, Kepler's physical astronomy, (New York: Springer,
1987), pp. 67–75.
^ "[Kepler's] revolutionary role lay in his successful attempt to
solve the problem of uniting astronomy and natural philosophy which
had been sought for two thousand years." P. 484 in Wilbur Applebaum,
Astronomy after Kepler: Researches and Problems," History
of Science, 34 (1996): 451–504.
^ "We have found Tycho's mature planetary observations to be
consistently accurate to within about 1'." P. 30, n. 2 in Gingerich,
Owen; Voelkel, James R. (1998). "Tycho Brahe's Copernican Campaign".
Journal for the History of Astronomy. 29: 2–34.
^ The average error of Tycho's stellar observations, as recorded in
his observational logs, varied from 32.3" to 48.8" for different
instruments. Table 4 in Walter G. Wesley, "The Accuracy of Tychho
Brahe's Instruments," Journal for the History of Astronomy, 9(1978):
^ An error of as much as 3' was introduced into some of the stellar
positions published in Tycho's star catalog due to Tycho's application
of an erroneous ancient value of parallax and his neglect of
refraction. See Dennis Rawlins, "Tycho's 1004
Star Catalog", DIO 3
(1993), p. 20.
^ Holmes, John,
Astronomy Ancient and Modern (1751)
^ Bryant, Walter W. (1907). A History of Astronomy. p. 53.
^ Brasch, Frederick (October 1931), "The Royal Society of London and
its Influence upon Scientific Thought in the American Colonies", The
Scientific Monthly, 33 (4): 338.
^ Morison, Samuel Eliot (March 1934), "The Harvard School of Astronomy
in the Seventeenth Century", The New England Quarterly, 7: 3,
^ Lewis D. Eigen, "Ladies of the Laboratory 2: How in a Few Months
Late in the 19th Century One Man Who Had Little Interest in Gender
Equality Hired More Female Astronomers than the World Had Ever Known",
Scriptamus, December 2009
Historians of astronomy
Scholars Past. Willy Hartner, Otto Neugebauer, B. L. van der Waerden
Scholars Present. Stephen G. Brush, Stephen J. Dick, Owen Gingerich,
Bruce Stephenson, Michael Hoskin, Alexander R. Jones, Curtis A. Wilson
Astronomer-historians. J. B. J. Delambre, J. L. E. Dreyer, Donald
Osterbrock, Carl Sagan, F. Richard Stephenson
Aaboe, Asger. Episodes from the Early History of Astronomy.
Springer-Verlag 2001 ISBN 0-387-95136-9
Aveni, Anthony F. Skywatchers of Ancient Mexico. University of Texas
Press 1980 ISBN 0-292-77557-1
Dreyer, J. L. E. History of
Astronomy from Thales to Kepler, 2nd
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 ISBN 0-86078-868-7
Evans, James (1998), The History and Practice of Ancient Astronomy,
Oxford University Press, ISBN 0-19-509539-1 .
Antoine Gautier, L'âge d'or de l'astronomie ottomane, in
L'Astronomie, (Monthly magazine created by
Camille Flammarion 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 ISBN 0-19-725944-8
Hoskin, Michael. The History of Astronomy: A Very Short Introduction.
Oxford University Press. ISBN 0-19-280306-9
McCluskey, Stephen C. Astronomies and Cultures in Early Medieval
Cambridge University Press
Cambridge University Press 1998 ISBN 0-521-77852-2
Pannekoek, Anton. A History of Astronomy.
Dover Publications 1989
Pedersen, Olaf. Early Physics and Astronomy: A Historical
Introduction, revised edition.
Cambridge University Press
Cambridge University Press 1993
Pingree, David (1998), "Legacies in
Astronomy and Celestial Omens", in
Dalley, Stephanie, The Legacy of Mesopotamia, Oxford University Press,
pp. 125–137, ISBN 0-19-814946-8 .
Rochberg, Francesca (2004), The Heavenly Writing: Divination,
Astronomy in Mesopotamian Culture, Cambridge University
Stephenson, Bruce. Kepler's Physical Astronomy, Studies in the History
Mathematics and Physical Sciences, 13. New York: Springer, 1987
Walker, Christopher (ed.).
Astronomy before the telescope. British
Museum Press 1996 ISBN 0-7141-1746-3
Neugebauer, Otto (1969) , The Exact Sciences in Antiquity (2
ed.), Dover Publications, ISBN 978-0-486-22332-2
Revello, Manuela (2013). "Sole, luna ed eclissi in Omero", in TECHNAI
4, pp. 13-32. Pisa-Roma: Fabrizio Serra editore.
DIO: The International Journal of Scientific History
Journal for the History of Astronomy
Journal of Astronomical History and Heritage
Wikimedia Commons has media related to History of astronomy.
Portal to the Heritage of Astronomy
Astronomiae Historia / History of
Astronomy at the Astronomical
Institutes of Bonn University.
Commission 41 (History of Astronomy) of the International Astronomical
Society for the History of Astronomy
Caelum Antiquum: Ancient
Astrology at LacusCurtius
Starry Messenger: Observing the Heavens in the Age of Galileo - an
exhibition from the Beinecke Rare
Book and Manuscript Library at Yale
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.
More information on women astronomers
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