A star chart is a

celestial map A star chart is a celestial cartography, celestial map of the night sky with astronomical objects laid out on a grid system. They are used to identify and locate constellations, stars, nebulae, galaxy, galaxies, and planets. They have been used ...

of the

night sky The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlig ...

with

astronomical object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...

s laid out on a grid system. They are used to identify and locate

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

nebula A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in ...

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...

, and

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

s. They have been used for human

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the motion, movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navig ...

since time immemorial. Note that a star chart differs from an

astronomical catalog An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, Galaxy morphological classification, morphology, origin, means of detection, or method of discovery. The olde ...

, which is a listing or tabulation of astronomical objects for a particular purpose. Tools using a star chart include the

astrolabe An astrolabe (; ; ) is an astronomy, astronomical list of astronomical instruments, instrument dating to ancient times. It serves as a star chart and Model#Physical model, physical model of the visible celestial sphere, half-dome of the sky. It ...

and

planisphere In astronomy, a planisphere () is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist i ...

History

Prehistory

A variety of archaeological sites and artifacts found are thought to indicate ancient made star charts. The oldest known star chart may be a carved ivory

Mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus.'' They lived from the late Miocene epoch (from around 6.2 million years ago) into the Holocene until about 4,000 years ago, with mammoth species at various times inhabi ...

tusk, drawn by early people from Asia who moved into Europe, that was discovered in Germany in 1979. This artifact is 32,500 years old and has a carving that resembles the constellation Orion, although it could not be confirmed and could also be a pregnancy chart. German researcher Dr Michael Rappenglueck, of the University of Munich, has suggested that drawing on the wall of the

Lascaux Lascaux ( , ; , "Lascaux Cave") is a network of caves near the village of Montignac, Dordogne, Montignac, in the Departments of France, department of Dordogne in southwestern France. Over 600 Parietal art, parietal cave painting, wall paintin ...

caves in France could be a graphical representation of the

Pleiades The Pleiades (), also known as Seven Sisters and Messier 45 (M45), is an Asterism (astronomy), asterism of an open cluster, open star cluster containing young Stellar classification#Class B, B-type stars in the northwest of the constellation Tau ...

open cluster An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

of stars. This is dated from 33,000 to 10,000 years ago. He also suggested a panel in the same caves depicting a charging bison, a man with a bird's head and the head of a bird on top of a piece of wood, together may depict the

Summer Triangle The Summer Triangle is an astronomical asterism in the northern celestial hemisphere. The defining vertices of this imaginary triangle are at Altair, Deneb, and Vega, each of which is the brightest star of its constellation ( Aquila, Cygn ...

, which at the time was a circumpolar formation. Rappenglueck also discovered a drawing of 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 sem ...

constellation in the

cave of El Castillo The Cueva del Castillo contains both a decorated cave and an archaeological site, within the complex of the Caves of Monte Castillo, in Puente Viesgo, Cantabria, Spain. The archaeological stratigraphy has been divided into around 19 layers, ...

(North of Spain), made in the same period as the Lascaux chart. Another star chart panel, created more than 21,000 years ago, was found in the La Tête du Lion cave ( fr). The bovine in this panel may represent the constellation Taurus, with a pattern representing the Pleiades just above it. A star chart drawn 5000 years ago by the Indians in Kashmir, which also depict a supernova for the first time in human history. The

Nebra sky disk The Nebra sky disc (, ) is a bronze disc of around diameter and a weight of , having a blue-green patina and inlaid with gold symbols. These symbols are interpreted generally as the Sun or full moon, a lunar crescent, and stars, including a cl ...

, a 30 cm wide bronze disk dated to 1600 BC, bears gold symbols generally interpreted as a sun or full moon, a lunar crescent, several stars including the Pleiades cluster and possibly the Milky Way.

Antiquity

The oldest accurately dated star chart appeared in ancient

Egyptian astronomy Egyptian astronomy started in prehistory, prehistoric times, in the Prehistoric Egypt, Predynastic Period. In the 5th millennium BCE, the stone circles at Nabta Playa may have made use of astronomical alignments. By the time the historical Ancie ...

in 1534 BC. The earliest known star catalogues were compiled by the ancient Babylonian astronomers of

Mesopotamia Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. Today, Mesopotamia is known as present-day Iraq and forms the eastern geographic boundary of ...

in the late 2nd millennium BC, during the

Kassite Period The Kassites () were a people of the ancient Near East. They controlled Babylonia after the fall of the Old Babylonian Empire from until (Chronology of the ancient Near East#Variant Middle Bronze Age chronologies, short chronology). The Kassi ...

(''ca.'' 1531–1155 BC). The oldest records of

Chinese astronomy Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The Ancient China, ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categori ...

date to the

Warring States period The Warring States period in history of China, Chinese history (221 BC) comprises the final two and a half centuries of the Zhou dynasty (256 BC), which were characterized by frequent warfare, bureaucratic and military reforms, and ...

(476–221 BC), but the earliest preserved Chinese star catalogues of astronomers Shi Shen and

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 ...

are found in the 2nd-century BC ''

Shiji The ''Shiji'', also known as ''Records of the Grand Historian'' or ''The Grand Scribe's Records'', is a Chinese historical text that is the first of the Twenty-Four Histories of imperial China. It was written during the late 2nd and early 1st cen ...

'' by the

Western Han The Han dynasty was an imperial dynasty of China (202 BC9 AD, 25–220 AD) established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC) and a warring int ...

historian

Sima Qian Sima Qian () was a Chinese historian during the early Han dynasty. He is considered the father of Chinese historiography for the ''Shiji'' (sometimes translated into English as ''Records of the Grand Historian''), a general history of China cov ...

. The oldest Chinese graphical representation of the night sky is a

lacquerware Lacquerware are objects decoratively covered with lacquer. Lacquerware includes small or large containers, tableware, a variety of small objects carried by people, and larger objects such as furniture and even coffins painted with lacquer. Before ...

box from the 5th-century BC

Tomb of Marquis Yi of Zeng The Tomb of Marquis Yi of Zeng () is an archaeological site in Leigudun Community (), Nanjiao Subdistrict (), Zengdu District, Suizhou (during the Spring and Autumn period called Sui County), Hubei, China, dated sometime after 433 BC. The tomb co ...

, although this depiction shows the positions of the

Chinese constellations Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenisti ...

by name and does not show individual stars. The

Farnese Atlas The Farnese Atlas is a 2nd-century CE Ancient Rome, Roman marble sculpture of Atlas (mythology), Atlas holding up a celestial globe. Probably a copy of an earlier work of the Hellenistic period, it is the oldest extant statue of Atlas (mythology) ...

is a 2nd-century AD Roman copy of a

Hellenistic era In classical antiquity, the Hellenistic period covers the time in Greek history after Classical Greece, between the death of Alexander the Great in 323 BC and the death of Cleopatra VII in 30 BC, which was followed by the ascendancy of the Roma ...

Greek statue depicting the

Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...

Atlas An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...

holding the

celestial sphere In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, ...

on his shoulder. It is the oldest surviving depiction of the

ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

constellations, and includes grid circles that provide coordinate positions. Because 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 o ...

, the positions of the constellations slowly change over time. By comparing the positions of the 41 constellations against the grid circles, an accurate determination can be made of the

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

when the original observations were performed. Based upon this information, the constellations were catalogued at . This evidence indicates that the

star catalogue A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the year ...

of the 2nd-century BC Greek astronomer

Hipparchus Hipparchus (; , ; BC) was a Ancient Greek astronomy, Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equinoxes. Hippar ...

was used. A

Roman era In modern historiography, ancient Rome is the Roman people, Roman civilisation from the founding of Rome, founding of the Italian city of Rome in the 8th century BC to the Fall of the Western Roman Empire, collapse of the Western Roman Em ...

example of a graphical representation of the night sky is the

Ptolemaic Egypt Ptolemaic is the adjective formed from the name Ptolemy, and may refer to: Pertaining to the Ptolemaic dynasty * Ptolemaic dynasty, the Macedonian Greek dynasty that ruled Egypt founded in 305 BC by Ptolemy I Soter *Ptolemaic Kingdom Pertaining ...

ian

Dendera zodiac The sculptured Dendera zodiac (or Denderah zodiac) is a widely known Art of ancient Egypt, Egyptian bas-relief from the ceiling of the ''pronaos'' (or portico) of a chapel dedicated to Osiris in the Dendera Temple complex, Hathor temple at Dende ...

, dating from 50 BC. This is a bas relief sculpting on a ceiling at the

Dendera Temple complex The Dendera Temple complex (Ancient Egyptian: ''Iunet'' or ''Tantere''; the 19th-century English spelling in most sources, including Belzoni, was Tentyra; also spelled Denderah) is located about south-east of Dendera, Egypt. It is one of the be ...

. It is a

depicting the

zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south celestial latitude of the ecliptic – the apparent path of the Sun across the celestial sphere over the course of the year. Within this zodiac ...

in graphical representations. However, individual stars are not plotted.

Medieval

The oldest surviving manuscript star chart was the Dunhuang Star Chart, dated to the

Tang dynasty The Tang dynasty (, ; zh, c=唐朝), or the Tang Empire, was an Dynasties of China, imperial dynasty of China that ruled from 618 to 907, with an Wu Zhou, interregnum between 690 and 705. It was preceded by the Sui dynasty and followed ...

(618–907) and discovered in the

Mogao Caves The Mogao Caves, also known as the Thousand Buddha Grottoes or Caves of the Thousand Buddhas, form a system of 500 temples southeast of the center of Dunhuang, an oasis located at a religious and cultural crossroads on the Silk Road, in Gansu p ...

Dunhuang Dunhuang () is a county-level city in northwestern Gansu Province, Western China. According to the 2010 Chinese census, the city has a population of 186,027, though 2019 estimates put the city's population at about 191,800. Sachu (Dunhuang) was ...

Gansu Gansu is a provinces of China, province in Northwestern China. Its capital and largest city is Lanzhou, in the southeastern part of the province. The seventh-largest administrative district by area at , Gansu lies between the Tibetan Plateau, Ti ...

Western China Western China ( zh, s=中国西部, l=, labels=no or zh, s=华西, l=, labels=no) is the west of China. It consists of Southwestern China and Northwestern China. In the definition of the Chinese government, Western China covers six provinces ...

along the

Silk Road The Silk Road was a network of Asian trade routes active from the second century BCE until the mid-15th century. Spanning over , it played a central role in facilitating economic, cultural, political, and religious interactions between the ...

. This is a scroll 210 cm in length and 24.4 cm wide showing the sky between

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...

s 40° south to 40° north in twelve panels, plus a thirteenth panel showing the northern circumpolar sky. A total of 1,345 stars are drawn, grouped into 257 asterisms. The date of this chart is uncertain, but is estimated as 705–10 AD. Su Song Star Map 2

During the

Song dynasty The Song dynasty ( ) was an Dynasties of China, imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Fiv ...

(960–1279), the Chinese astronomer

Su Song Su Song (, 1020–1101), courtesy name Zirong (), was a Chinese polymathic scientist and statesman who lived during the Song dynasty (960–1279). He exceled in numerous fields including but not limited to mathematics, astronomy, cartography, ...

wrote a book titled ''Xin Yixiang Fa Yao'' (New Design for the Armillary Clock) containing five maps of 1,464 stars. This has been dated to 1092. In 1193, the astronomer Huang Shang prepared a planisphere along with explanatory text. It was engraved in stone in 1247, and this chart still exists in the Wen Miao temple in

Suzhou Suzhou is a major prefecture-level city in southern Jiangsu province, China. As part of the Yangtze Delta megalopolis, it is a major economic center and focal point of trade and commerce. Founded in 514 BC, Suzhou rapidly grew in size by the ...

. In Muslim astronomy, the first star chart to be drawn accurately was most likely the illustrations produced by the Persian astronomer

Abd al-Rahman al-Sufi ʿAbd al-Raḥmān al-Ṣūfī (; 7 December 90325 May 986) was a Persian astronomer. His work '' '' ("''The Book of Fixed Stars''"), written in 964, included both textual descriptions and illustrations. The Persian polymath Al-Biruni wrote th ...

in his 964 work titled ''

Book of Fixed Stars ''The Book of Fixed Stars'' ( ', literally ''The Book of the Shapes of Stars'') is an Astronomy, astronomical text written by Abd al-Rahman al-Sufi (Azophi) around 964. Following Graeco-Arabic translation movement, the translation movement in the ...

''. This book was an update of parts VII.5 and VIII.1 of the 2nd century

Almagest The ''Almagest'' ( ) is a 2nd-century Greek mathematics, mathematical and Greek astronomy, astronomical treatise on the apparent motions of the stars and planetary paths, written by Ptolemy, Claudius Ptolemy ( ) in Koine Greek. One of the most i ...

star catalogue by

Ptolemy Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...

. The work of al-Sufi contained illustrations of the constellations and portrayed the brighter stars as dots. The original book did not survive, but a copy from about 1009 is preserved at the

Oxford University The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the second-oldest continuously operating u ...

. Perhaps the oldest European star map was a parchment manuscript titled ''De Composicione Spere Solide''. It was most likely produced in

Vienna Vienna ( ; ; ) is the capital city, capital, List of largest cities in Austria, most populous city, and one of Federal states of Austria, nine federal states of Austria. It is Austria's primate city, with just over two million inhabitants. ...

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

in 1440 and consisted of a two-part map depicting the constellations of the northern celestial hemisphere and the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

. This may have served as a prototype for the oldest European printed star chart, a 1515 set of woodcut portraits produced by

Albrecht Dürer Albrecht Dürer ( , ;; 21 May 1471 – 6 April 1528),Müller, Peter O. (1993) ''Substantiv-Derivation in Den Schriften Albrecht Dürers'', Walter de Gruyter. . sometimes spelled in English as Durer or Duerer, was a German painter, Old master prin ...

Nuremberg Nuremberg (, ; ; in the local East Franconian dialect: ''Nämberch'' ) is the Franconia#Towns and cities, largest city in Franconia, the List of cities in Bavaria by population, second-largest city in the States of Germany, German state of Bav ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

Early modern

During the European

Age of Discovery The Age of Discovery (), also known as the Age of Exploration, was part of the early modern period and overlapped with the Age of Sail. It was a period from approximately the 15th to the 17th century, during which Seamanship, seafarers fro ...

, expeditions to the southern hemisphere began to result in the addition of new constellations. These most likely came from the records of two Dutch sailors,

Pieter Dirkszoon Keyser Pieter Dirkszoon Keyser (occasionally Petrus Theodorus; – 11 September 1596) was a Dutch navigator and celestial cartographer who mapped several constellations on the southern celestial hemisphere. Voyages and star observation Little is ...

and

Frederick de Houtman Frederick de Houtman ( – 21 October 1627) was a Dutch explorer, navigator, and colonial governor who sailed on the first Dutch expedition to the East Indies from 1595 until 1597, during which time he made observations of the southern cel ...

, who in 1595 traveled together to the

Dutch East Indies The Dutch East Indies, also known as the Netherlands East Indies (; ), was a Dutch Empire, Dutch colony with territory mostly comprising the modern state of Indonesia, which Proclamation of Indonesian Independence, declared independence on 17 Au ...

. Their compilations resulted in the 1601 globe of

Jodocus Hondius Jodocus Hondius (Latinized version of his Dutch name: ''Joost de Hondt'') (17 October 1563 – 12 February 1612) was a Flemish and Dutch engraver and cartographer. He is sometimes called Jodocus Hondius the Elder to distinguish him from h ...

, who added 12 new southern constellations. Several other such maps were produced, including

Johann Bayer Johann Bayer (; 1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer). He was born in Rain in 1572. In 1592, aged 20, he began his study of philosophy and law at the University of Ingolstadt, after which he ...

's ''

Uranometria is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mang (''Christophorus Mangus'') under the full title (from Latin: ''Uranometria, containing charts of all the constellations, drawn by a new method an ...

'' in 1603. The latter was the first atlas to chart both celestial hemispheres and it introduced the

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

s for identifying the brightest stars using the Greek alphabet. The ''Uranometria'' contained 48 maps of Ptolemaic constellations, a plate of the southern constellations and two plates showing the entire northern and southern hemispheres in stereographic polar projection. Polish astronomer

Johannes Hevelius Johannes Hevelius Some sources refer to Hevelius as Polish: * * * * * * * Some sources refer to Hevelius as German: * * * * *of the Royal Society * (in German also known as ''Hevel''; ; – 28 January 1687) was a councillor and mayor of Danz ...

published his Firmamentum Sobiescianum star atlas posthumously in 1690. It contained 56 large, double page star maps and improved the accuracy in the position of the southern stars. He introduced 11 more constellations, including Scutum, Lacerta, and

Canes Venatici Canes Venatici ( ) is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...

Modern

In 1824

Sidney Hall Sidney Hall (1788?–1831) was a British engraving, engraver and cartography, cartographer well known and popular for his early nineteenth century atlases containing maps of the United Kingdom and of the Ancient history, ancient world reproduced ...

produced a set of star charts called

Urania's Mirror ''Urania's Mirror; or, a view of the Heavens'' is a set of 32 astronomical star chart cards, first published in November 1824. They are illustrations based on Alexander Jamieson's ''A Celestial Atlas'', but the addition of holes punched in them ...

. They are illustrations based on

Alexander Jamieson Alexander Jamieson (1782–1850) was a Scottish writer and schoolmaster, now best known as a rhetorician. He has been described as effectively a professional textbook writer. After the failure of his school, he worked as an actuary. Life Some of ...

's ''A Celestial Atlas'', but the addition of holes punched in them allowed them to be held up to a light to see a depiction of the constellation's stars.

References

External links

An online guide to using a star chartThe world's earliest manuscript Star Chart
from Dunhuang on the Silk Road

Star charts

Sky Chart
– Free Northern Sky Chart Cutout.
Planispherium
– Free Northern Sky Chart Cutout in Latin

– Free star charts
Geody Star Charts
– Free (CC-by-sa) printer friendly star charts for several latitudes and times of the year
An online star chartMonthly sky maps for every location on Earth

The Evening Sky Map
– Free monthly star charts and calendar for northern hemisphere, southern hemisphere, and equatorial sky watchers.
Sky Map Online
– Free interactive star chart (showing over 1.2 million stars up to magnitude 12)
Stellarmap.com
– Online map of the stars (requires compatible browser such as Chrome, Opera, Firefox, Safari or IE9). {{DEFAULTSORT:Star Chart Navigation Map types * * * + * Celestial cartography