History of astronomy

The astronomer Claudius Ptolemy with the personified Astronomia from the encyclopedia Margarita Philosophica by Gregor Reisch , 1503

The history of astronomy encompasses the entire cultural history of mankind . The astronomy (astronomy) was already in the Stone Age from the unity of sun and star observation and cultic worship of the stars . Classical geometric astronomy developed from free-eyed observations of the starry sky and its cycles, the oldest areas of which are positional astronomy and ephemeris calculation . The invention of the telescope (1609) and special measuring devices for the further development of celestial mechanics and modern astrophysics and the use of radio and space telescopes gave a strong impetus .

Astronomy determines the self-image of humans and their perception of their position in the universe , nowadays mainly through the discussions about the origin of the universe and the search for habitable exoplanets and extraterrestrial life .

Preliminary remarks

Day of the week heptagram with the corresponding astronomical symbols ; Clockwise, starting at the top: Sunday ( Sun ), Friday ( Venus ), Wednesday ( Mercury ), Monday ( Moon ), Saturday ( Saturn ), Thursday ( Jupiter ), Tuesday ( Mars )

At all times have the sky , the fixed stars , including the Milky Way and the seven along the zodiac moving celestial bodies namely the sun , the moon and its phases of the moon , the Mercury , the Venus , the Mars , the Jupiter and Saturn are observed, after which the seven days of the week in use today were named. Although Uranus is also visible to the naked eye in the night sky, its apparent brightness is surpassed by more than a thousand stars, so that it was only discovered at the end of the 18th century.

Special celestial objects that can be seen with the naked eye include, for example, the star cluster of the Pleiades , the Orion Nebula or galaxies such as the Andromeda Galaxy or the Magellanic Clouds . Comets , meteors and novas , which appear less frequently and irregularly and are sufficiently bright , were always visible to the naked eye. For orientation in the starry sky , constellations could be formed using the brightest fixed stars and different constellations between the celestial bodies could be observed.

All celestial objects seem to revolve around the two celestial poles ; the northern sky counterclockwise in the northern hemisphere , and the southern sky clockwise in the southern hemisphere . Circumpolar celestial bodies are always above the horizon in relation to the observation point , and all others are only visible above the horizon between their daily rising in the east and setting in the west .

Due to the lack of light pollution , and with good atmospheric visibility , it was possible to make celestial observations of objects up to the sixth size class with the naked eye until the 19th century . Observations of less bright celestial objects can only be made from the surface of the earth from light protection areas or with optical devices .

Because of the cycle of precession of the earth's axis , historical observations must take into account that the Sun's vernal equinox, also known as the Aries point , moves once along the ecliptic through the entire zodiac within around 28,000 years . Since the corresponding determinations were made in antiquity, the vernal equinox is now in the constellation Pisces , and there is an offset between the astrological signs of the zodiac and the constellations of the same name .

Astronomical interpretation of a paleolithic painting in the Lascaux cave as a large summer triangle

Prehistoric sky observations

To equinox the sun goes from Ballon d'Alsace seen behind the Belchen in the Black Forest on

Nebra Sky Disc

Scheme of the Neolithic circular moat by Goseck - directions of rising and setting of the sun at the winter solstice represented by yellow lines, the white one marks the meridian

There are only a few indications of prehistoric observations of the sky, including Paleolithic wall paintings around 20,000 years old in the Lascaux cave , which may depict the Pleiades, the zodiac and the summer sky . Also in the valley of the Vézère in southwest France under a rock roof , the Abri Blanchard , an approximately 30,000 year old eagle wing bone with lined up dot markings was found, the number and arrangement of which may be related to the moon phases. Both finds come from the Upper Paleolithic . However, the lack of meaningful archaeological finds does not prove that sky observation played no role for the people of the Paleolithic. The observation of astronomical phenomena and attempts to interpret them are at least attested to in today's hunter-gatherer cultures , such as the Aborigines .

The location of the sources changed noticeably for the Neolithic period . Because for agriculturally producing crops planning the sowing and harvesting are of decisive importance, as is sufficient stocking throughout the year. With the growing dependency on changing seasonal conditions, the interest in a possible foresight grows. Therefore, the cyclically repeating changes in the apparent movement of the sun and moon in the sky - over the course of a day, month, year - receive special attention. Their changed position in the starry sky in the twilight and night is also noticed, their orbit in the sky and that of some other stars. The beginnings of a calendar calculation require a good knowledge of the sun's path and moon phase cycle . This makes it possible to predict some sky phenomena and to align the sequence of seasonal activities according to their dates and to agree on them together.

Rites , cults and religious interpretations of the possible cause of the observed heavenly phenomena and their cycles are closely related. In this respect it is conceivable that the transition to agriculture contributed significantly to the development of various astral cults . In its beginnings, astronomy was linked to astrology in both Western and Asian cultures.

For simple observations for calendar purposes at the same location, the positions of the sunrise on the horizon or the length of the shadow cast by elevations have always been considered. For this purpose, geographical references to mountains, such as between the five Belchen in the Belchen system , can be used. The archaeological finds from the late Bronze Age in Central Europe that can be related to calendars include the tall gold hats found in southern Germany and France , around 3000 years old. These cones, embossed in one piece and decorated in several rows, are interpreted as part of the sacred headgear of priests of a sun cult .

The Nebra Sky Disc is the oldest concrete representation of the sky; it dates from the early Bronze Age and is around 4000 years old. In particular, the arc of the horizon, executed as a gold application, and the perforations on the outer edge suggest that it also fulfilled calendar functions. The Goseck district moat , built around 7000 years ago, is one of the oldest man-made solar observatories. Around two millennia later, a complex was built in southern England , the expansion of which with megalithic stone circles created a place of worship that is still impressive today, Stonehenge . The geographical orientation of the building and the direction of special sight lines show astronomical references. Something similar can be shown worldwide for cult buildings from many epochs, as well as numerous burials are aligned according to cardinal directions, such as those of the Cord Ceramic culture in the Copper Age . Often nothing is known about the cults originally practiced, but references to solstices and equinoxes are obvious .

With archaeoastronomy , there has been a special field of its own since the 1970s, which deals with the research of these buildings and finds from an astronomical point of view.

Astronomy in the early advanced civilizations

Darkening of the full moon during a total lunar eclipse

The first lunar eclipse that is said to have been observed is that of January 17, 3380 BC. BC, which is said to have been recorded by the Maya in Central America. This assumption is controversial, however, as research assumes that the Maya started their calendar after 3373 BC at the earliest. Introduced. Isolated theories that they had started earlier cannot yet be proven.

The star map fitted into the starry sky on the celestial table of Tal-Qadi when measuring the ecliptical latitude of Venus eleven days before it reached the Golden Gate of the Ecliptic (between Aldebaran and the Pleiades ) with the brightest stars and today's constellations

The oldest known representation of the night sky is on a limestone slab that was found during excavations at the temple of Tal-Qadi in Malta and dated to the 3rd millennium BC.

Darkening of the sun during a solar eclipse by the new moon

In China the first solar eclipse occurred in 2137 BC. Recorded.

The Egyptians and Mesopotamians also watched the sky and worshiped astral deities . On June 6, 763 BC The first definitely datable observation of a solar eclipse occurs in Mesopotamia.

Egyptian and Mesopotamian astronomy

The sky view was also linked to mythology and religion in the ancient civilizations of North Africa and the Middle East .

Egypt

→ Main article : Astronomy in Ancient Egypt

In contrast to northern Europe, where research into prehistoric astronomy can only be based on archaeological knowledge, there existed for Egypt up to the 3rd millennium BC. Written records of the techniques and importance of ancient Egyptian astronomy going back to the 3rd century BC . The astronomical "researches" and interpretations of that time must also be understood in the context of the sun cult that prevailed in Egypt at that time and were used essentially to calculate the exact occurrence of the annual Nile flood .

The Egyptians used twelve stars to measure time during the night , with the length of the first and last time period being adjusted depending on the season. The mythological background of the Twelve Night Stars ("Stars that never set") was the belief that the nocturnal crossing of the deceased kings with the sun god Re took place under the protection of the Twelve Guardians of the Night Sky . It began with the onset of dusk and ended with sunrise. Constellations also played an important role. They contained the stars of different gods. The oldest representation of the night sky can be found on the underside of a coffin in Assiut, another in the burial chamber of Senenmut (Thebes grave TT353 ). The representation of the constellations, which then became common - also in the tomb of King Sethos I around 1279 BC. BC - does not match the current classification of the constellations.

It is not known which measuring methods the Egyptian astronomers used exactly. In the Egyptian calendar played Sirius , a special role because its heliacal rising from approximately v 2000th BC announced the Nile flood . Originally, Sirius seems to be associated with the beautiful festival of the desert valley . Since the Egyptian year was 365 days long, the date of the heliacal rising of Sirius changed with time; after a cycle of 1440 to 1460 years it fell again on the same date in the Egyptian calendar. The history of the ancient Egyptian religion shows that the priests watched over their astronomical knowledge and still around 221 BC. A reform of the calendar with an improved year length of 365.25 days reversed. This may be due to the fact that the priests were responsible for calculating the religious feast days, which slowly shifted on a 365-day calendar; they would have lost this task with a corrected calendar with 365.25 days. Also noteworthy is a view that Tycho took 2000 years later: that Venus and Mercury orbit the sun, but the sun revolves around the earth.

Mesopotamia

3200-year-old stele from Babylonia - the scene shows the deity Nanaja enthroned , before whom King Meli-Sipak leads his daughter; The sun, moon and star are the symbols of the deities Šamaš , Sin and Ištar .

In Mesopotamian astronomy, in addition to the early beginning, precise observations - in the 3rd millennium BC. BC - it is remarkable how precisely the series of measurements were recorded on thousands of clay tablets .

At that time the Babylonians knew all the important celestial cycles with astonishing accuracy: u. a. the synodic month with 29.53062 days (instead of 29.53059), the Venus and Mars orbits (only 0.2 or 1 hour incorrect) or the 18-year Saros cycle of eclipses. Our hour counter and the 360 ​​° were developed in Babylon. The constellations near the ecliptic were divided into three paths of the sun , which were assigned to the gods Anu , Enlil and Ea .

Astrological predictions and the preoccupation with heavenly omens were a central concern of the priest astronomers there. The Babylonians and Assyrians kept records of their astronomical observations in their archives, which even according to conservative estimates date back to the third millennium BC.

For example, the Assyrian MUL.APIN clay tablets dating from 2300 to 687 BC contain BC exact lists of the heliacal rising of the constellations in the sky. They were always created in three sentences and used until around 300 BC. Duplicated as needed. It can be assumed that the Greek astronomer Eudoxos of Knidos used much of this data for his star catalogs .

The Sumerians created their calendar according to the astronomical constellations . Thousands of traditional clay tablets in cuneiform , which are mainly assigned to the archives of Uruk and Ninive , contain astronomical texts. Already in the early 3rd millennium BC Venus was described as the star of Inanna . Old cylinder seals and texts that mentioned Inanna as the embodiment of the planet Venus prove the Sumerian knowledge of the time: Inanna, as Venus, all foreign countries also see you shining. I want to offer her a song as Lord of Heaven .

Based on long series of observations, Babylonian astronomers developed mathematical series that made it possible to calculate the positions of the celestial bodies (see ephemeris ) and to predict certain celestial phenomena. Already around 1000 BC They were able to isolate complex superimpositions of periodic phenomena in the individual periods and thus calculate them in advance.

Nabu-rimanni (approx. 560-480 BC) is the earliest Babylonian-Chaldean astronomer known by name . Important successors are Kidinnu (approx. 400–330), Berossos (around 300) and Soudines (around 240 BC).

Ancient astronomy

Beginnings of Greek astronomy

An armillary sphere as it was used until the 17th century

Simple forms of the armillary sphere were already used by the Babylonians and later further developed by the Greeks , as were sundials and the gnomon . The division of the zodiac into 360 degrees, which probably goes back to the Egyptian deans , was adopted by the Greeks as well as individual observations and the planet names and periods of the Babylonians. But they did not take into account the mathematical methods underlying the Mesopotamian tradition; The approach was now different, since the Greek philosophers understood the universe primarily geometrically , not arithmetically .

Today's knowledge of the beginnings of Greco-Ionian astronomy and the extent to which Mesopotamian influenced them is very sketchy. It can be assumed that the loss of books in late antiquity and in the Middle Ages also affected numerous astronomical works. In some cases, they came back to Europe much later, indirectly through Arabic translations.

The Greek philosophers and astronomers

→ Main article : Ancient astronomy

Artist's impression of the geocentric worldview according to Ptolemy

Already very early literary texts offer indications of the preoccupation of the ancient Greeks with the processes in the sky. Both Homer and Hesiod mention astronomical realities; the zodiac is partially attested in Homer. Hesiod, on the other hand, even developed a theory of world creation . The two authors do not yet reveal a deeper understanding of space; so they describe morning and evening stars as different objects. At least by the time of Plato this error was corrected thanks to Babylonian information; this advance was later attributed to Pythagoras . The prediction of a solar eclipse in the year 585 BC has been handed down. By the philosopher Thales of Miletus .

The pre-Socratics developed up to the 5th century BC Different astronomical models. Among other things, they invented increasingly more precise methods of measuring time, such as sundials , the principles of which they probably adopted from the Babylonians. Anaximander , a contemporary and student of Thales, postulated the geocentric view of the world by being the first to describe the sky as a spherical shell ( sphere ) with the earth in the center. Earlier cultures thought of the sky as a hemisphere just above the earth's disk without touching the problem of where the stars could be between rising and setting outside of myths . However, Anaximander did not yet understand the earth as a sphere.

Classical Greek culture first practiced astronomy out of a scientific interest in the actual processes in the sky, regardless of the practical use of the calendar and religious and astrological motives. The remarkably accurate measurement of the circumference of the earth by Eratosthenes around 220 BC is famous . Chr .: He compared the shadows of different lengths that the light of the sun casts when it is at its zenith, on the one hand in Alexandria and on the other hand in Syene on the same day and explained this phenomenon with the fact that the locations are at different latitudes on a sphere . Less well known is the attempt of Aristarchus of Samos to measure the distance to the sun in relation to the moon distance, which turned out to be very incorrect due to insufficient measurement accuracy (it was determined too short by a factor of 20), but was methodologically correct.

The Antikythera Mechanism dates back to around 100 BC. Modern research suggests that it was used to predict the motion of celestial bodies.

Hipparchus of Nicaea and others developed the astronomical instruments that remained in use until the invention of the telescope almost two thousand years later, such as an angle measuring instrument, a kind of advanced armillary sphere with which coordinates on the celestial sphere could be determined. It was introduced by Eratosthenes under the name Astrolabe and also described by Ptolemy .

One of the few surviving technical objects from Greek times is the Antikythera mechanism , the earliest known device with a system of cogwheels (around 100 BC). The mechanism is interpreted as an analog computer for the advance calculation of the celestial body movements. It may have been constructed by Poseidonios (135–51 BC).

Another important preparatory work for the astronomy of later times was done by Aristotle (384–322 BC), who recognized the principle of the camera obscura . In his comprehensive presentation of physics , which continued into the Middle Ages, he described the natural movement of heavenly bodies and also gravity.

The heliocentric worldview

The work of Ptolemy around 150 AD represented the climax and - according to current knowledge - also the conclusion of ancient astronomy. On the basis of the work available at that time (Hipparchus and possible others), Ptolemy developed and gave the worldview later named after him With the Almagest, a standard work on astronomy emerged, on whose star catalog astronomers referred to beyond the Renaissance . The Romans valued astronomy as part of education but did not develop it any further. Rather, she was interested in astrology with its claim to predict the future. Remnants of ancient specialist knowledge were preserved in the Eastern Roman Empire , but the cultural exchange with the Latin-speaking scholars of Western and Central Europe largely came to a standstill at the beginning of the early Middle Ages.

Alternatives to the geocentric worldview

Alternatives to the geocentric view of the world have been suggested repeatedly. Hiketas of Syracuse (around 400 BC) made the stars stand still and the earth rotated. Other Pythagoreans believed that there was a central fire in the center of the universe , orbited by the earth, the sun and the planets. Philolaos also postulated a counter-earth so that the heavenly bodies would reach the sacred number ten. In the 3rd century BC, Aristarchus of Samos proposed a heliocentric view of the world with the sun as the center of rest. He also argued - as in the 4th century Herakleides Pontikos  - for a daily axis rotation of the earth with an immovable sky.

The geocentric worldview with an immovable earth around which all spheres rotate daily, however, remained the generally accepted model until Nicolaus Copernicus , who followed Aristarchus in 1543. The heliocentric design by Copernicus made an alternative appear conceivable, which became more plausible through Johannes Kepler's knowledge of the elliptical planetary orbits. But many still doubted the immeasurably empty space between Saturn's orbit and the nearest fixed stars until Friedrich Wilhelm Bessel was able to determine a star distance of ten light years for the first time in 1838.

Cornerstones of development in antiquity

The insights and achievements of ancient astronomers can be noted:

• the ability to calculate and predict the movements of planets and the occurrence of eclipses ( Saros cycle )
• the knowledge that the earth is spherical (Aristotle, 384–322 BC: first assumptions of the spherical shape due to circular earth shadows in lunar eclipses; around 200 BC by Eratosthenes of Alexandria: first approximately correct calculation of the earth's circumference using the highest position of the sun in various places)
• the suggestion of alternatives to the geocentric worldview
• around 150 BC First catalog of stars (about 1000 stars) created by Hipparchus von Nikaia and Archimedes
• the discovery of the precession motion of the earth. This discovery is attributed to Hipparchus (around 150 BC). Since then, the permanent change in the coordinates of the fixed stars in the night sky and thus also the equatorial coordinates right ascension and declination has been known.

Pliny the Elder , who wrote an overall presentation of the natural history of the time in AD 60, also treated astronomy as celestial science in contrast to astrology.

Astronomy in India, China, America and Australia

The system of today's celestial coordinates was developed early in South and East Asia . But while in China the astronomical observations were kept more as a chronicle, in India they were linked as early as 1000 BC. With a profound cosmology . In contrast, relatively little is known about the astronomical background of the American high cultures.

India

Jantar Mantar Observatory in Jaipur

In the Indus culture from 1000 BC onwards A detailed cosmology with the divine natural forces heaven, earth, sun (which was interpreted as a glowing stone), moon, fire and eight cardinal points. According to the mythology of the time, the world originated from a sacred egg made of silver (primordial earth) and gold (starry sky) with the atmosphere as an intermediate layer . The sun was considered the divine eye of the universe, the lunar cycle as a giver of time and life. The planetary orbits run between the sun and the polar star .

The Vedic Astronomy has survived in heavily encrypted verses, which makes their classification difficult in a larger cultural context. In general, however, it is very similar to the Babylonian , which - depending on the interpretation and dating - can mean Babylonian models for the Vedic astronomers and also the opposite effect. Both positions are discussed in the history of astronomy, but an essentially independent development in both cultural areas is also conceivable. Because some of the similarities, such as the division of the zodiac into 360 degrees with twelve constellations, can also be derived directly from nature. The year is rounded to 360 days, but the months are counted as today. However, in the system of ancient Indian astronomy, two years of 360 days are always followed by one with 378 days. The day has different lengths depending on the season (" Muhurtas " with 9.6 to 14.4 hours).

In addition, an astonishing correspondence to Christianity and also to the views of Teilhard de Chardin is worth mentioning: God is understood as a spirit who loves the world, whose son keeps an eye on the development of the universe.

Indian astronomy experienced a renewed upswing around 500 AD with the astronomer Aryabhata , to whom, among other things, the invention of the concept of the number “ zero ” is ascribed. Important facilities are the five observatories that Jai Singh II had built in the early 18th century in Delhi and Jaipur , among other places . The largest of these, the Jantar Mantar in Jaipur, consists of fourteen structures for the observation and measurement of astronomical phenomena.

Melanesia

Above all, the highly developed navigation with sun and stars should be mentioned here, which was a prerequisite for colonizing the island world . Orientation methods have been handed down

• with the Pole Star and the Southern Cross , as well
• for east and west courses, bearing stars close to the horizon, such as in the eagle , whose direction changes little because of the almost vertical star orbits .

The first night of the creation story has stars, but still without the sun and moon. The divine separation of heaven and earth was carried out with a cult staff, similar to that on Orthodox icons . The abode of God and the unborn is in the Milky Way , and the souls are the original form of the constellations .

China

An essential element of Chinese philosophy is the harmony of heaven, man and earth. Celestial phenomena were considered from this main point of view. It was the endeavor of the Chinese - so the interpretation in the current literature of the People's Republic of China - to foresee disturbances of this harmony and thus to end the age of belief in incalculable foreign control.

Old Chinese star map

The astronomers in the Chinese Empire not only had to deal with the calendar , but also with the prediction of extraordinary celestial phenomena (e.g. solar eclipses) and also with state astrology. They already knew around 2000 BC The lunisolar year with a 19-year switching rule because of the lunar knots (see also Saros cycle ). There was a scientific office whose origins can no longer be determined, but can be traced back to well before the birth of Christ. This office continued until 1911, and four main servants were assigned to him: the chief astronomer (Fenxiangshi), who was responsible for the uninterrupted sky view, the chief rologist (Baozhangshi), who was responsible for the records, the chief meteorologist (Shijinshi) for weather phenomena and solar eclipses , and the keeper of time (Qiehushi), who was responsible for the calendar calculation.

The old Chinese chronicles are still considered reliable and relatively complete - also because the officials vouched for the reliability of their results with their lives. It is said that the astronomers Xi and He because of the failure to predict the solar eclipse of October 3, 2137 BC. Were beheaded.

Sunspots have been observed in China since around the turn of the ages , which is possible with the naked eye at sunrise and sunset, as well as novae and supernovae , which were called guest stars , and even as early as 613 BC. The Comet Halley .

According to the worldview of imperial China, there are five areas of the heavens, the four cardinal points and the center, which includes the circumpolar area and represents the imperial palace.

Influences from the Near East can be traced back to pre-Christian times based on Hellenism , and they seem to have become more intense later. In the Middle Ages, instruments similar to the armillary sphere were used, which probably go back to contacts with the Greek and Islamic world. In addition, Chinese star maps have been handed down for ship navigation .

From around 1600 Christian missionaries brought the knowledge and measurement methods of European astronomy to China. After an initial mistrust, their superiority was recognized by the imperial family, and the new specialist art put an end to traditional astronomy. So it came about that the imperial observatory in the Qing dynasty was traditionally re-established and managed by Jesuits such as Ignaz Kögler or Anton Gogeisl .

The Japanese historian of science Yabuuchi Kiyoshi (1906–2000) conducted intensive research on the history of Chinese astronomy . He published his findings in several presentations.

America

Piedra del Sol , an Aztec calendar stone

Little is known about the astronomical worldview of the Indian high cultures, but cult buildings (e.g. step temples with precise orientation) and observatories provide numerous references. Most of the writings and codices were destroyed by the conquistadors . Without a doubt, however, the calendar calculation and the calculation of the planetary cycles were highly developed - see the Mayan and Aztec calendars . In 1479 the Aztecs created the " sun stone ".

The orbital times of the five clear-sighted planets were sometimes known to only a few minutes. The duration of the month coincided with today's values ​​to 6 decimal places - which means less than 1 hour of errors per century .

Astronomy in the Middle Ages

→ Main article : Cosmology of the Middle Ages

Two particularly striking celestial phenomena have been handed down from the Middle Ages : A new star in the constellation Taurus (" Supernova 1054 ") was observed worldwide in 1054 AD , which was also visible during the day for weeks ( Crab Nebula , Messier catalog M1 ), and on June 25, 1178 the monk and chronicler Gervasius of Canterbury observed a luminous phenomenon on the crescent moon, which could have been a meteor impact (formation of the moon crater Giordano Bruno ?).

Western Europe

Depiction of Cepheus from the 9th century, from the Leiden Aratea

During the centuries of the Great Migration , Central and Western Europe had largely lost contact with the ancient Greco-Roman cultural knowledge. Ancient astronomical literature remained accessible and studied only in the Greek-speaking Byzantine Empire . In the Latin-speaking West, however, very little of this tradition was available until the 12th century. There the teaching canon of the Seven Liberal Arts was retained , in which astronomy formed one of the four parts of the quadrivium , but in practice at the monastery schools of the early Middle Ages mostly only the trivium was taught, which no longer comprised scientific material.

In the course of Charlemagne's reform policy , astronomy was upgraded as a subject: the emperor obliged all cathedral churches to set up schools where astronomy had to be taught alongside the other subjects of the quadrivium (geometry, arithmetic and music); it was also about the ability of the clergy to calculate the date of Easter . However, this reform, which flagged again after a few years or decades, had little overall effect, and the clergy's knowledge of astronomy remained poor.

In the Carolingian period, however, copies of the astronomical didactic poems of Aratos were made , such as the magnificently illustrated Leiden Aratea , which were probably commissioned at the court of Louis the Pious . Together with Aratos, the descriptions of the constellations of Hyginus in the Poeticon Astronomicon formed the standard works that were widespread until the end of the late Middle Ages. The knowledge of the classic constellation myths came mainly from these two works. The illustrations of the manuscripts are of high artistic quality. However, the positions at which the illustrators placed the stars in the pictures have little or nothing in common with the actual firmament; rather, they were chosen so that they fit the characters well.

The few other surviving ancient works on astronomy were initially only copied in the monasteries, but with the beginning of scholasticism in the 11th century, they were increasingly commented on. However, confirming, supplementing or refuting them through one's own observations did not correspond to the medieval understanding of science. Astronomy was therefore understood at that time as an essentially closed subject, which did not require one's own observation of the starry sky to understand it. The sudden appearance of a supernova in 1054 was one of the first events to shake the prevailing static understanding of the cosmos.

In the late Middle Ages there was a greater interest in astronomy, and astronomical works were also spread with the early printing of books . The Vienna School of Astronomy , starting with Johannes von Gmunden (1380–1442) , gave important impulses to celestial studies . His successor Georg von Peuerbach as the world's first astronomy professor (University of Vienna 1453) became a predecessor of Copernicus through revisions by Ptolemy. His pupil Regiomontanus published not only copies of the two ancient works mentioned above, but also numerous astronomical books, including a Calendarium , which by the standards of the time can be considered a bestseller. In 1472 he succeeded in measuring the angular diameter of a comet for the first time . Regiomontanus was empirical and ready to question traditional ideas. His own observation and comparison with the results of ancient science should, in his opinion, renew astronomy and help to find “the truth”. With this attitude he became a pioneer of the heliocentric worldview alongside Nikolaus von Kues .

Georg Tannstetter wrote his description of the Viri Mathematici (1514; German: Mathematische Männer), an early approach to the writing of the history of science, about Regiomontanus and other astronomers and mathematicians working in Vienna .

Following the example of Aristotle, the monk Roger Bacon built the first apparatus in the form of a camera obscura for observing the sun and correctly described the structure of a lens in 1267.

Islamic astronomy

Arabic astrolabe around 1208

After astronomy was still taught in the Roman Empire , but no longer expanded, progress was only made again after the Islamic expansion . The leading Islamic scholars were often court astronomers or court mathematicians of the regional Muslim rulers. In the old cultural centers affected by the Arab expansion, they took over much of the scientific expertise of antiquity. The achievements in Arabic or in the Arabic language, including the astronomical considerations and inventions of an Avicenna , mainly concerned astrometry :

• Precise observations of the sky - also for astrological purposes, although Islam was reluctant to see an attempt to look into the future and astrology did not allow
• Creation of star catalogs , naming of bright stars (still in use today)
• Further development of the astrolabe etc., precise measurement of the ecliptic obliqueness .

Theory of lunar eclipses, al-Biruni

Without telescopes , however, the Islamic astronomers were unable to significantly expand on ancient knowledge. The geocentric view of the world remained generally accepted, only details such as epicycles or spheres were initially discussed, corrected and expanded where possible. Because of the time elapsed since these theories were set down in which the errors had accumulated, the discrepancies between the ancient theories and observation were evident to Islamic scholars. In the 16th century, when the Copernican change took place in Europe too, Islamic scholars increasingly rejected the ancient worldviews. It is not known to what extent these two paths were independent, or whether Copernicus had indirect knowledge of Islamic developments.

Some of the progressive achievements of Islamic astronomers ultimately had no impact, such as the Samarkand observatory built by Ulug Beg at the beginning of the 15th century . As the best of its time, it was razed and left to decay after just a generation by Ulug Beg's successors. Other Islamic observatories suffered a similar fate, only the Maragha observatory, built by Nasir Al-din al-Tusi in 1264, survived its builder by almost forty years before it was closed between 1304 and 1316. Although the Islamic astronomers recognized the flaws of the ancient theories and improved them, their most important achievement from today's point of view was the preservation, translation and in some cases expansion of ancient natural science, something European culture was hardly capable of during the early Middle Ages. With the end of Islam's heyday in the 15th century, however, Islamic astronomy was hardly able to give European astronomy any impetus, and its achievements were eventually overtaken and forgotten by the European renaissance.

The level of development of Islamic astronomy is also exemplary for the astronomy of other cultures that reached a similar level, but could not develop beyond this (also without telescopes). The Indian or Vedic astronomy, the Chinese and the pre-Columbian astronomy of the Indian high cultures are particularly worth mentioning . All these cultures possessed an observational knowledge accumulated over many centuries, with which the periodic phenomena of the planetary system could be predicted.

Late medieval astronomers under the guidance of the Muse Astronomia

Cultural exchange with Islam

Through the cultural exchange with the Islamic countries, especially after the establishment of the crusader states in the Middle East in the 12th century and in the course of the Reconquista ( translation school of Toledo ), the works of Aristotle and Ptolemy came back to the West via the intermediate step of the Arabic translation . It was only Byzantine emigrants who finally brought the ancient works to Central Europe after the conquest of Constantinople by the Ottomans in the original or in Greek copies. Even in the High Middle Ages, philosophical-theological considerations of the world structure were more in focus than concretely observed celestial events. The different models of the celestial spheres, such as those described in the rediscovered works of Aristotle and Ptolemy, were discussed in detail and, for example, questions about the number of spheres, or whether the fixed star sphere rotates once a day or the earth. However, there was no doubt about the principles of this cosmology.

Astronomy in the Renaissance

Nicolaus Copernicus

The age of the Renaissance marked the heyday of classical astronomy as a science of the geometrical structure of the universe , a science which, however, was only beginning to address itself to the investigation of the physical background of the star movement. Up until the Renaissance, astrology and astronomy were not mutually exclusive, but rather two complementary areas of knowledge. Up until the 17th century, many astronomers also created horoscopes for their clients, but did not see them as their main activity. Astronomy only deals with the positions of the stars and planets and their exact calculation; astrology tried to interpret these positions with regard to earthly events. Astronomical knowledge was therefore the prerequisite for astrology. The inaccuracy of the astronomical calculations and model concepts was partly blamed for the persistent and unmistakable flawedness of the astrological predictions, from which a major incentive arose for their improvement.

The work of Nicolaus Copernicus gave European astronomy a new direction. After observing the moon against the background of the fixed stars, he doubted the geocentric view of the world and worked out a model in which the sun is equated with the center of the world at rest. In 1543 it was published in his book De revolutionibus orbium coelestium .

Kepler's model of the solar system . From:  Mysterium Cosmographicum (1596)

Tychos wall quadrant around 1600

The Astronomus (1568) by Jost Amman , probably depicting the Nuremberg doctor, humanist and astronomer Melchior Ayrer.

From 1519 to 1522 the expedition led by Fernão de Magalhães (Magellan) succeeded in sailing the earth for the first time, including the discovery of the Strait of Magellan , the Philippines and the rediscovery of the Magellanic clouds in the southern sky (and the date line). Nicolaus Copernicus ushered in a new era in astronomy. In May 1543, in his book De revolutionibus orbium coelestium, he mathematically demonstrated that the planetary movements can also be correctly described with a heliocentric view of the world. In 1568 Daniele Barbaro improved the camera obscura by using a lens and thus did significant preparatory work for the astronomers of later generations. Tycho Brahe measured the orbits of comets for the first time and drew conclusions about their distance (1577) - the great "astronomical" distances became tangible. Tycho previously observed a supernova (1572) and the orbit of Mars, and after Johann Bayer had published the first modern star catalog ( uranometria ) in 1603 , Johannes Kepler rewrote Kepler's 1st and 2nd law of planetary motions, named after him, in his book Astronomia Nova in 1609 the sun (his previously published works paved the way for his Astronomia Nova ). Now there was a correct description of the planetary movements from a heliocentric point of view. Tycho Brahe had done the necessary preparatory work with the wall quadrant he had developed. This instrument replaced the armillary sphere , which had been in use since ancient times, as a universal instrument . Due to their accuracy and the first good coverage of larger parts of Mars' orbit, Brahe's position measurements then enabled Johannes Kepler to discover the laws of planetary motion.

The invention of the telescope at the beginning of the 17th century marked the turning point in astronomy. With its help Galileo Galilei discovered the four inner moons of Jupiter and the phases of Venus . Some of these discoveries were published in Sidereus Nuncius in 1610 . This weakened the Ptolemaic worldview lastingly. It became clear that the Copernican worldview as well as the geocentric model of Brahe was compatible with the observations. A decisive proof was neither theoretically nor practically possible at that time. The subsequent dispute with the church ended with the legal victory of the Inquisition against Galileo, but it established a problematic relationship between the church and the natural sciences .

The 17th and 18th centuries

The European princes increasingly promoted astronomy at their courts as a symbol of their culture and education, which resulted in a personal and financial upswing in research. In addition, national observatories were founded, such as the Royal Greenwich Observatory or the Paris Observatory . Their main task was to provide tables for seafaring and to solve the length problem, but they also did astronomical research. While the research of the court astronomers was tied to the personal interests of the princes, longer-term research traditions could develop at the national observatories , so that such independent observatories assumed a leading role in research by the beginning of the 19th century at the latest.

17th century

Wilhelm Herschel's 40- foot telescope from 1789

At the beginning of the 17th century, astronomers began to observe celestial bodies with the help of newly discovered optical instruments. The first functional telescope was built in the Netherlands around 1608. It is a matter of dispute who the actual inventor was.

In 1609 Johannes Kepler published his work Astronomia Nova with the first two Kepler's laws . The astronomer Simon Marius rediscovered our neighboring galaxy , the Andromeda Nebula , through the telescope in 1612 (it was discovered by the Persian astronomer Al-Sufi in the 10th century ). As early as 1610, Galileo Galilei published his book Sidereus Nuncius , in which he reported on his new discoveries with a telescope. In 1632 his "Dialogue on the Two World Systems" appeared, but on June 22, 1633 he had to renounce the heliocentric worldview. He died on January 8, 1642. In 1619 Johann Baptist Cysat discovered new, physically related binary star systems . This led to speculation about planetary systems around other stars, a possibility that had previously only been discussed philosophically, based on Giordano Bruno . In 1635, Jean-Baptiste Morin was one of the first astronomers to succeed in observing the brightest star in the northern sky, Arcturus, in the Bear Guardian, even in the daytime .

In 1651 Giovanni Riccioli published the first map of the moon; In 1655/56 Christiaan Huygens and Giovanni Domenico Cassini succeeded in discovering the rings of Saturn , the moon Titan and the Orion Nebula (Huygens, published 1659 in Systema Saturnium ). Huygens was the first to recognize the true nature of Saturn's rings .

In 1668 Isaac Newton came up with the idea of bundling light with mirrors instead of lenses made of glass - the invention of the mirror telescope . In 1669 he also succeeded in discovering the attraction of mass ( gravitation ) and the first theory to explain the phenomenon “light” as particle radiation, so that the understanding of the cosmos was slowly placed on a new basis. With the epochal work Philosophiae Naturalis Principia Mathematica , published in 1687, he laid the first foundations of astrophysics by tracing Kepler's laws back to his theory of gravitation.

Comet Hale-Bopp as captured by Geoff Chester on March 11, 1997

During this time, Cassini discovered the Saturn moons Japetus in 1671 , Rhea in 1672 , Tethys and Dione in 1684 . From 1683 to 1686, Cassini and Nicolas Fatio de Duillier found and declared the zodiacal light .

Calculating the speed of light

In 1676, Ole Rømer proved by delaying the eclipses of the Jupiter moon depending on their distance from the earth that the speed of light is finite. After his decisive preparatory work, it was calculated for the first time by Christiaan Huygens in 1678 at around 213,000 km / s (the current value is c = 299,792.458 km / s) by using the transit time (22 min = 1320 s) from Römer and the orbit diameter ( 280 million km in today's units, the true value is 299 million km) used by Cassini (published in Treatise on Light , 1690).

The 18th century

The astronomy of the 18th century is mainly characterized by two broad lines:

• In observing astronomy a . a. the improvement of telescopes (first achromatic lenses around 1730, large reflector telescopes , new eyepieces, micrometers , etc.) and the construction of efficient observatories (keyword astronomical tower )
• In theory, the development of celestial mechanics (based on Newton's law of gravitation) and first models of cosmology (formation of the solar system, star clusters , structure of the Milky Way ).

This led to important discoveries such as

• Planet Uranus , periodic comets , differential solar rotation
• Proper motion of the sun and nearby stars, fixed star aberration
• the first determination of the real size of the solar system by calculating the astronomical unit from a Venus transit .

Predicting a comet

→ Main article : Comet research

Newton concluded in his Principia that comets move around the sun similar to planets, but in elongated ellipses (“Diximus Cometas esse genus Planetarum in Orbibus valde excentricis circa Solem revolventium”). By comparing the traditional comet sightings, recurring objects should show themselves. Edmond Halley took on this task and published his calculations in 1705. He postulated that the comet of 1682 must be identical to earlier appearances in 1607 and 1531, and derived its return for 1758/59 from this. The arrival of this prognosis was a great triumph for Newtonian theory, but it was also unique. Many comets were predicted during this time, including two more by Halley. It was not until 1822 that a small comet (only visible through a telescope) was confirmed to be periodic (2P / Encke) . The fact that a farmer from Saxony ( Palitzsch ) and not the professional astronomers in Paris or London discovered the 1P / Halley was a result of the popularization of modern science and also caused a sensation.

Star clusters and nebulae

With increasingly powerful telescopes, the exploration of foggy celestial objects became an important field of work. The brighter star clusters have already been recognized as such. In the case of weak clouds of fog and gas , the indirect vision method was used.

In 1774, Charles Messier created the first systematic directory of “fog objects”, the Messier catalog that is still used today . The main purpose, however, was to differentiate between newly discovered comets.

"Everything is in motion" ( Panta rhei )

In 1718 Halley put forward the thesis of the proper motion of the fixed stars by comparing them with ancient star maps .

In 1728 James Bradley discovered in the unsuccessful attempt to measure a parallax of the "fixed stars" that the position of each star fluctuates over the course of the year ( aberration ). This was also recognized by most of the then still numerous followers of the Tychonic view of the world as evidence of the movement of the earth. In addition, the movement of light could be confirmed and the speed of light calculated more precisely.

In 1755 Immanuel Kant drafted the first theories about the formation of our solar system resulting from purely mechanical processes .

In 1761, several observers of the Venus transit on June 6th recognized the first extraterrestrial atmosphere.

In 1769, James Cook took part in Tahiti as one of several observers of the Venus transit on June 3, which was the most accurate earth-sun determination for well over a century.

The discovery of Uranus

Galileo recorded Neptune in 1612

The planet Uranus, although visible to the naked eye under favorable conditions, was not recognized as a planet by ancient astronomers. After the invention of the telescope, it was first sighted by John Flamsteed on December 23, 1690 and cataloged as a fixed star "34 Tauri". On March 13, 1781 Wilhelm Herschel observed it as a small disc and initially thought it was a comet. However, Nevil Maskelyne suspected that it could be another planet. In 1787 Herschel discovered the Uranus moons Titania and Oberon and in 1783 the sun's own motion in the direction of the constellations Hercules and Lyra . Our sun finally became one of the many stars that move in the system of the Milky Way .

19th century

Map of the surface of Mars according to Schiaparelli

During this epoch, the knowledge of the physical principles of astronomical observation methods and light developed - and subsequently astrophysics . Some also speak of the century of the refractor , which made the development of large lens telescopes possible thanks to Fraunhofer's completely color-pure lenses . They expanded knowledge of the planetary system , the Milky Way and, through precise measurement of geographical lengths, also the measurement of the earth. Joseph von Littrow's “Miracles of Heaven” became a model book for popular science, saw numerous editions and made investments in new observatories plausible for the general public .

Physics of light and spectral analysis

1800 discovered William Herschel , the infrared radiation of the Sun, 1802 William Wollaston the absorption lines in the solar spectrum. Independently of this, Josef Fraunhofer described the Fraunhofer's lines in the solar spectrum named after him in 1813 and invented the spectroscope a year later . The research of Gustav Robert Kirchhoff and Robert Wilhelm Bunsen made it possible in 1859 to explain the absorption lines in the solar spectrum by energetic processes in gas atoms and molecules. This laid one of the most important foundations for modern astronomy, from which astrophysics developed.

The celestial objects were divided into classes with the help of spectroscopy , which could later be traced back to physical similarities. In 1890 a group of women astronomers , including Williamina Fleming , Antonia Maury and Annie Jump Cannon , began to work out the classification of stars according to their spectrum. These spectral classes are still an important research method today.

Astrophotography

Another big step was the addition of photography to the human eye as an observation instrument . The first lightfast photograph was made by Joseph Nicéphore Nièpce in 1826 . In 1840 John William Draper took the first picture of the moon using a daguerreotype . With increasingly more sensitive photo emulsions, the observations became more objective and easier to document. On the other hand, hours of exposure opened up the possibility of exploring faint objects in much greater detail than visually. One of the first astronomers to use astrophotography was the Jesuit Angelo Secchi , director of the Vatican Observatory; he is also considered to be the pioneer of spectral analysis.

From around 1890 onwards, exposure lasting several hours made it possible to photograph nebulas that were barely visible, such as the North American Nebula or Barnard's Loop ; Edward Barnard discovered numerous dark nebulae of the Milky Way. In Heidelberg, the photographic discovery of many minor planets was possible thanks to their short trajectories. With the help of photographic surveys of the sky , the first comprehensive nebula catalogs such as the NGC were also created .

Success with the new telescopes

In 1838 Friedrich Wilhelm Bessel succeeded in proving a fixed star parallax for the first time with the Fraunhofer heliometer : 2 years of measurements on 61 Cygni showed a periodic shift of 0.30 "± 0.02", resulting in the distance of this star to 10 light years. Thus the universe had "enlarged" more than ten times compared to the ideas of the 18th century.

In 1846 the solar system also expanded - with the discovery of Neptune (see below). And the giant telescopes from Herschel and Lord Rosse showed the exact structure of nebulae , star clusters and, for the first time, the spiral arms of nearby galaxies. From 1880, the light intensity of new giant telescopes enabled the spectroscopic analysis of gas planets and their atmospheres. Through the positional astronomy of distant stars, Newcomb succeeded in establishing an exact inertial system of celestial coordinates.

Alvan Graham Clark discovered the Sirius companion ( Sirius B) predicted by Bessel in 1844 in 1862 . This extremely dense dwarf star became the first of the white dwarf type . In 1877 Asaph Hall found the two moons of Mars and Schiaparelli the so-called " Martian channels " - as a result, speculations about "Martians" received a tremendous boost. In 1898 Gustav Witt reported the discovery of the near-Earth asteroid Eros , which was soon used for precise distance measurements.

The discovery of Neptune

Inspired by Herschel's success in discovering Uranus, the astronomers searched for other planets and found what they were looking for in the objects of the asteroid belt . Since Uranus had been cataloged as a star a century earlier without recognizing it as a planet, enough data soon became available to detect disturbances in Uranus' orbit. Because of these disturbances, another planet was mathematically predicted, which was finally to be found in Neptune in 1846 by Johann Gottfried Galle . Galileo had already seen Neptune on December 27, 1612, but did not recognize him as a planet.

The 20th century

1900-1930

In 1900 Max Planck published Planck's law of radiation ; an indication of the entropy of the universe and pioneer of quantum theory . In 1901, Charles Dillon Perrine, together with George Willis Ritchey, observed gas nebulae around the star Nova Persei , which apparently moved faster than light , and a few years later he discovered two moons of Jupiter . In 1906 Max Wolf discovered the first Trojan ( Achilles ) and around the same time Johannes Franz Hartmann discovered the first indications of the existence of interstellar matter .

In 1913, Henry Norris Russell developed the so-called Hertzsprung-Russell diagram based on the work of Ejnar Hertzsprung . This is a process based on spectral analysis , from which indications of the evolutionary state of stars can be derived.

On June 30, 1908, the giant impact occurred the Tunguska - meteorites (40 km ² devastated) and 1920 in South West Africa (now Namibia ) the discovery of the heaviest iron meteorites of all time ( Meteorite Hoba , about 60 tons, 2.7 m × 2, 7 m × 0.9 m). 1923 succeeded u. a. Edwin Hubble provided evidence that the Andromeda Nebula (M 31) lies far outside the Milky Way , i.e. that there are other galaxies as well. In 1927, Georges Lemaître found the expansion of the universe with the help of the redshift proven by Milton Lasell Humason . In 1929, Hubble convincingly demonstrated a linear relationship between redshift and the distance of galaxies. Although his calculations have since been improved several times, the fundamental quantity of cosmology calculated in this way bears his name ( Hubble constant ). The Hubble time resulting from this quantity denotes the point in time at which the expansion of the universe began mathematically ( Big Bang ). Hubble himself calculated about 2 billion years; today a value of almost 14 billion years is postulated.

Neptune, which had been held responsible for Uranus' orbital deviations, had been found in 1846, but there were still inexplicable deviations in the orbits of the two planets. So the search continued for a hypothetical ninth planet, " Transneptune ".

During this search Percival Lowell photographed Pluto in 1915 , but did not recognize it as a planet at the time. It was not until February 18, 1930 that Clyde Tombaugh discovered him in the Lowell Observatory founded by Lowell by comparing some sky images on photographic plates with the blinking comparator . Until 2006, Pluto was counted as the ninth planet. Since then it has belonged to the newly created class of dwarf planets .

Mid 20th century

In the course of his work at the observatory on the Pic du Midi de Bigorre , Bernard Lyot found that the surface of the moon has properties of volcanic dust and that sandstorms occur on Mars . In 1931 Karl Guthe Jansky found the radio source " Sagittarius A ". In the following years, in 1933, Walter Baade and Fritz Zwicky also developed their theories about the transition from supernovae to neutron stars : The density of matter there had to correspond to the density of the atomic nuclei. The answer to the question of what is going on in stars before they collapse to such neutron stars, succeeded in 1938 Hans Bethe and Carl Friedrich von Weizsacker , the hydrogen - fusion to helium discovered in the CN-cycle (stellar fusion process, CNO cycle ; in the same year Nicholson found the 10th and 11th moons of Jupiter, Lysithea and Carme ). It could therefore be assumed that stars would light up and burn through hydrogen fusion until their hydrogen supply was thermonuclearly burned out. Then there is a “helium flash”, as a result of which helium is fused into heavier elements . In 1965, Kippenhahn, Thomas, Weigert and other astronomers and nuclear physicists found out that the fusion of hydrogen and helium in the giant star can also take place side by side (from approx. Three solar masses). The final stage of these processes is then a black hole .

The first radar contact with a celestial body was made as early as 1946, on January 10th (first radar echo from the moon, path length 2.4 seconds). 1951 followed the discovery of the cosmic 21 cm radio emission (from interstellar hydrogen), later the discovery of the 2.6 mm radiation (from carbon monoxide). Radio radiation from electrical discharges was received for the first time in the Venusian atmosphere in 1956. In 1964 the 3K background radiation was discovered (“echo of the big bang”). The radio astronomy was invented.

The observed orbital speed of stars is higher in the outer regions of galaxies than is to be expected on the basis of visible matter. This observation was the first important indication of the existence of dark matter

The first studies of the orbital speeds of stars in spiral galaxies by Vera Rubin since 1960 showed that the orbital speed was well above expectations, especially in the outer regions of the galaxies. The concept of dark matter resolves this contradiction between general relativity and observation. Although many other observations support the dark matter hypothesis, there is still no direct evidence of a dark matter particle to date (2020). Dark matter forms an important pillar of the current standard model of cosmology.

On May 12, 1971, the first German radio telescope went into operation in Effelsberg, Eifel . But further research was also carried out in optical astronomy: in 1973 James Van Allen carried out a systematic survey of the sky, 31,600 stars and 500 galaxies were registered per square degree down to a brightness of only 20 ^m ), i.e. 1.3 billion stars and 20 million galaxies (with approx. 200 billion stars each). Meanwhile, in 1974 Stephen Hawking drafted his theory of the emission of virtual particles from black holes . On March 29, 1974, Mariner 10 was the first probe to reach the innermost planet Mercury , supported by the swing-by technology on the planet Venus on February 5, 1974. Further Mercury passages took place on September 21, 1974 and March 16, 1975. The rings of Uranus were first described on March 10, 1977 .

From the mid-1970s onwards, many activities in astronomy and space travel focused on the question of whether there were other habitable or even inhabited worlds. A first active attempt to establish contact with extraterrestrial civilizations was made on November 16, 1974 (transmission of a 1.679 kB radio signal to the globular cluster M13; signal arrival there: around the year 27,000 AD). In 1976 Joachim Trümper succeeded in discovering a stellar super magnetic field via 58 keV radiation from the gyrating electrons at HZ Herculis: 500 · 10 ⁶ Tesla (Earth's magnetic field on the surface: approx. 50 · 10 ⁻⁶ Tesla). In 1977 Charles Kowal found the first centaur Chiron (also a planetoid, diameter 200 to 600 km, orbit radius 8.5 to 18.9 AU).

Jupiter close-up from Voyager 1 (1979)

Space probes

→ Main article : History of space travel

On March 3, 1972, NASA launched the Pioneer 10 probe . On December 3, 1973, it was the first space probe to fly past the planet Jupiter. The sister probe Pioneer 11 took off on April 6, 1973, passed Jupiter on December 3, 1974 and was the first probe to pass Saturn on September 1, 1979.

Voyager probe type

NASA launched Voyager 1 on September 5, 1977, which successfully passed Jupiter on March 5, 1979 after a journey of 675 million km, followed by Saturn in November 1980. On August 20, 1978, Voyager 2, the most successful swing-by spacecraft, was launched of all time in the outer solar system (mission data: Jupiter passage 9 July 1979 Saturn passage, Uranus flyby in January 1986, Neptune passage 1989), and even when she went on the trip, reported James W. Christy , the discovery of Pluto moon Charon . In 1977/78, organic molecules were first discovered in interstellar matter in the distant universe . B. acetic acid, methyl cyan, aminomethane, ethanol etc., a radio astronomical indication of a possible chemical evolution . Unmanned space travel reached the limits of our solar system: 1979/1980 discovery of numerous Jupiter and Saturn moons with Pioneer 11 and Voyager 2. In 1983, Pioneer 10 was the first space probe to pass Pluto's orbit - eleven years after its launch. 1984 First photograph and first flight through the Saturn ring.

The 1980s and 1990s

The ISEE-3 probe flew through a comet's tail for the first time (1985, September 11) (with gas analysis: ISEE-3 probe at Giacobini-Zinner ). In stellar astronomy, the supernova of 1987 was considered the sensation of the 1980s (February 24: first registration and photography of a supernova outbreak in the Large Magellanic Cloud (LMC), whose neutrinos reached Earth before the first optically perceptible signals ). The instruments available to astronomers got better, more accurate and more complicated. As part of NASA's Great Observatory Program, four extremely successful telescopes were launched, which made important astronomical observations possible over many years. On April 24, 1990, NASA announced the launch of the Hubble Space Telescope . The new observation device enabled - free of interference from the earth's atmosphere - sky recordings of new, great resolution in the following years. On August 6, 1993, nitrogen ice was discovered on Pluto (instead of the previously suspected methane ice ). This telescope should collect important knowledge for more than 20 years. However, other telescopes were also started, the images of which allowed investigations outside the optical wavelength range. These were in particular the space telescopes Chandra (X-ray astronomy) and Spitzer (infrared astronomy). The Hipparcos satellite was also an important mission . The result was the Hipparcos catalog , the most accurate star catalog to date with over 100,000 precisely measured stars (brightness, star locations, parallaxes, proper movements).

Probes also continued to explore the solar system: Galileo reached the planetoid Gaspra on October 29, 1991 and was at Ida on August 28, 1993 , Ulysses flew over the south solar pole on September 13, 1994 and even into the Galileo landing capsule on December 7, 1995 Jupiter's atmosphere : For the first time, the gas envelope of a gas planet could be examined spectroscopically. Alan Hale and Thomas Bopp published the discovery of the comet on July 22, 1995 at Hale-Bopp near Jupiter's orbit. The comet reached an apparent magnitude of −1 ^m in March 1997 . Indications of extraterrestrial life are said to have been discovered in 1996 in the Antarctic meteorite ALH 84001 (age 3.6 billion years), which originated from Mars (controversial).

In the late 1990s, observations of type Ia supernovae and the analysis of their respective redshifts led to the discovery of the accelerated expansion of the universe. This accelerated expansion can already be described in Albert Einstein's general theory of relativity by adding the so-called cosmological constant . Dark energy is responsible for this accelerated expansion , about the nature of which very little is known and which, according to current research, forms the dominant form of energy in the universe.

Planets outside the solar system

With the discovery of the first non-stellar celestial body outside of our planetary system, astronomy made a leap forward in terms of exoplanet search: On December 12, 1984, Mc Carthy et al. a. the first discovery of a non-stellar celestial body outside of the solar system, IR astronomical: it turned out to be a " brown dwarf " at star Van Briesbroeck 8 (distance 21 light years, 30 to 80 Jupiter masses). In the mid-1990s, exoplanets, ie planets outside the solar system, were found for the first time, first around a pulsar , then around a main sequence star in 1995 . Since then, the number of known exoplanets has increased steadily.

Conclusion on developments in the 20th century

The Hubble Space Telescope, Earth in the background

The understanding of the physical world through astronomy is based on Arthur Eddington's proposal from 1920 to consider nuclear fusion as the energy source of the stars, and the recognition of the spiral nebulae as extragalactic objects by Edwin Hubble in 1923 and his idea of ​​an expanding universe from 1929, the he developed as milestones after comparing the distance and flight speed of the galaxies . The model of the universe expanding out of a big bang is generally accepted today.

Albert Einstein provided the basis for many theories of modern astrophysics with his special and general theory of relativity . For example, the above-mentioned nuclear fusion is based on the equivalence of mass and energy , certain extreme objects such as neutron stars and black holes require the general theory of relativity for description, and cosmology is also largely based on this theory.

The findings of quantum and particle physics of the 20th century were also of crucial importance for a better understanding of the universe . Many astronomical observations could not be explained without knowledge of the particles and forms of radiation in quantum physics. Conversely, astronomical observation is an important source of knowledge for quantum physicists, since high-energy radiation from the cosmos reaches the earth and provides a deeper understanding.

A 900 light-year wide section of the central region of the Milky Way, taken in the X-ray range

With the beginning of space travel in the second half of the 20th century, astronomy had the opportunity to visit some of its research objects located in the solar system directly and to carry out scientific analyzes on site. But at least as important was the removal of the limitations of the earth's atmosphere, with which satellite-based observatories of ultraviolet astronomy , X-ray astronomy and infrared astronomy opened new wavelength ranges and thus new windows into the universe, each of which yielded previously unimagined knowledge. With the research of neutrinos of the sun and the supernova 1987A , the observation of particle showers of cosmic rays and the construction of gravitational wave detectors , modern astronomy also began for the first time to study other types of radiation than electromagnetic radiation . At the same time, telescopes such as the Hubble Space Telescope or the Very Large Telescope offered visual astronomy new possibilities for observation.

The 21st century

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Cryovolcanic activity on Enceladus

At the beginning of the 21st century, Mars was an important place of investigation in the solar system. With the help of various Mars probes, Mars could be precisely mapped from orbit. NASA rover missions confirmed the former occurrence of liquid water on the surface of Mars, among other things through the detection of sedimentary rocks. In the outer solar system, the Cassini-Huygens mission achieved important successes. In addition to a better understanding of the Saturn atmosphere and the Saturn rings , these were in particular the in-depth investigations of the ice moons Titan and Enceladus . The latter has an underground ocean and shoots water fountains into space, which form the E-ring of Saturn. In addition, the Kuiper Belt could be explored more precisely through terrestrial observations . This led to the discovery of a wide variety of Trans-Neptunian objects . The large number of these objects and the similarity of these objects to Pluto ultimately led to its downgrading as a dwarf planet by the IAU in 2006 .

The infrared missions 2MASS and WISE discovered many other small asteroids in the solar system as well as several brown dwarfs in the wider area of ​​the solar system. Using the data from WISE in 2013, the Luhman 16 system , which is only 6.5 light-years away and consists of two brown dwarfs, was discovered.

The proportion of matter and energy in the universe at the present time (above) and at the time of decoupling (below), 380,000 years after the Big Bang. (Observations of the WMAP mission, among others). According to the data from the PLANCK space telescope ( ESA , March 21, 2013), the values ​​are slightly corrected compared to WMAP: Visible matter: 4.9%, dark matter: 26.8%, dark energy: 68.3%, age of the universe: 13.82 billion years. The term “atoms” stands for “normal matter”.

The two missions WMAP and Planck brought further insights into the investigation of the distribution of matter in the young cosmos by examining the background radiation .

During the exploration of the exoplanets the first evidence of atmospheres of the extraterrestrial worlds was obtained and with the help of the Kepler space telescope (2009-2018) thousands of these distant worlds were discovered. In 2016, the discovery of Proxima Centauri b , an exoplanet around our closest neighbor, Proxima Centauri , was announced.

An important milestone in the exploration of the universe was the first successful detection of gravitational waves with the LIGO detector in 2015 , whereby a collision of 2 black holes could be detected. In 2017, GW170817 from the galaxy NGC 4993 was the first to detect a gravitational wave signal and a gamma-ray burst . The cause was probably the collision of two neutron stars . Various survey projects are mapping the sky, including SDSS and the Gaia probe . Billions of different objects can now be cataloged and examined in this way. In 2019, the first photo of a black hole was taken using the Event Horizon Telescope , a network of interconnected radio telescopes .

See also

Portal: Astronomy  - Overview of Wikipedia content on the topic of astronomy

• History of astronomy and astrophysics in Antarctica
• History of Tibetan Astronomy
• Astronomy time table
• Timeline solar research
• List of discoveries of planets and their moons
• List of German astronomers of the early modern period
• Archaeoastronomy
• Popular Gastronomy

swell

• Ptolemy : Almagest . Approx. 150.
• Nicolaus Copernicus : De revolutionibus orbium coelestium . 1543.
• Johann Bayer : Uranometria . 1603.
• Johannes Kepler : Astronomia Nova . 1609; Harmonice Mundi . 1619.
• Galileo Galilei : Dialogo sopra i due massimi sistemi . 1632.
• Isaac Newton : Philosophiae Naturalis Principia Mathematica . 1687. ( originals as PDF )
• Wilhelm Herschel : On the Construction of the Heavens . 1785.
• Pierre-Simon Laplace : Traité de Mécanique Céleste . 1799.
• Angelo Secchi : Portfolio fotografiche delle principali fasi lunari . 1858.
• Arthur Stanley Eddington : The Internal Constitution of Stars . 1926.
• Edwin Hubble : The realm of the nebulae . 1936.

bibliography

• Jürgen Hamel : Bibliography of the astronomical literature up to 1700 . Friends of the Archenhold Observatory and the Zeiss Planetarium Berlin ( online )

literature

• M. Razaullah Ansari: History of oriental astronomy. Kluwer, Dordrecht 2002, ISBN 1-4020-0657-8
• Louis Bazin: About astronomy in ancient Turkish times (= treatises of the humanities and social sciences class of the Academy of Sciences and Literature in Mainz. Born in 1963, No. 5).
• Friedrich Becker : history of astronomy . Bibliographic Institute, Mannheim 1968
• Thomas Bührke: Great moments in astronomy. From Copernicus to Oppenheimer. CH Beck, Munich 2001, ISBN 3-406-47554-X .
• Heather Couper, Nigel Henbest: The History of Astronomy. Frederking & Thaler, Munich 2008, ISBN 978-3-89405-707-7
• Wolfgang R. Dick, Jürgen Hamel (ed.): Contributions to the history of astronomy . Vol. 5. Acta Historica Astronomiae. Harri Deutsch, Frankfurt / M. 2002. ISBN 3-8171-1686-1 .
• Wolfgang R. Dick, Jürgen Hamel (ed.): Contributions to the history of astronomy . Vol. 8. Acta Historica Astronomiae. Harri Deutsch, Frankfurt / M. 2006.
• Jürgen Hamel: History of Astronomy . Kosmos-Franckh, Stuttgart 2002, ISBN 3-440-09168-6
• John L. Heilbron: The Oxford guide to the history of physics and astronomy. Oxford Univ. Press, New York 2005, ISBN 978-0-19-517198-3
• Ernst Künzl : Celestial Globes and Star Maps. Astronomy and astrology in prehistoric times and antiquity. Theiss, Stuttgart 2005. ISBN 3-8062-1859-5 .
• Yasukatsu Maeyama: Astronomy in Orient and Occident - selected papers on its cultural and scientific history. Olms, Hildesheim 2003, ISBN 3-487-11931-5
• Jean Meeus: Astronomical Algorithms , Barth, Leipzig 2000 ² , ISBN 3-335-00400-0
• John North: Vieweg's History of Astronomy and Cosmology. Springer, Berlin 1997, ISBN 3-540-41585-8
• Harry Nussbaumer: The worldview of astronomy. vdf, Zurich 2007, ISBN 978-3-7281-3106-5
• Harry Nussbaumer: Revolution in the sky. How the Copernican Revolution changed astronomy. vdf, Zurich 2011, ISBN 978-3-7281-3326-7
• Anton Pannekoek: A history of Astronomy , Dover, New York 1989 (reprinted 1961), ISBN 0-486-65994-1
• Robert Powell: History of the Zodiac. Tübingen 2007, ISBN 978-3-937077-23-9
• Günter D. Roth : history of astronomy (astronomers, instruments, discoveries). Kosmos-Franckh, Stuttgart 1987, ISBN 3-440-05800-X .
• Ernst Seidl: Heaven. Ideal image and understanding of the world . MUT, Tübingen 2011, ISBN 978-3-9812736-2-5 .
• Rudolf Simek : Earth and Cosmos in the Middle Ages: The worldview before Columbus. Beck, Munich 1992, ISBN 3-406-35863-2 .
• Bartel Leendert van der Waerden : Awakening Science. Volume 2: Beginnings of Astronomy . Birkhäuser, Basel 1980, ISBN 3-7643-1196-7 .
• Bartel Leendert van der Waerden: The astronomy of the Greeks. An introduction. Scientific Book Society, Darmstadt 1988, ISBN 3-534-03070-2 .

Web links

Commons : History of Astronomy  - Collection of Images, Videos and Audio Files

Wikisource: Astronomy  - Sources and Full Texts

• Working group on the history of astronomy of the Astronomical Society
• Martins Starworld: History of Astronomy
• Manfred Holl: Overview of the astronomy-historical topics
• Ove von Spaeth: Selected bibliography on ancient astronomy
• History of astronomy in Nuremberg with a chronological and thematic overview as well as an encyclopedia
• The astronomie-rara platform with the most important historical works of astronomy in digitized form (cooperation project between the library of the Deutsches Museum in Munich and the ETH library)
• www.leifiphysik.de/..astronomie..geschichte
• History of Astronomy - Internet dossier on the radio series by WDR 5 Leonardo
• Paris Observatory s digital library

Individual evidence

1. ↑ Jürgen Hamel : History of Astronomy. In texts from Hesiod to Hubble. 2nd ext. Ed., Magnus-Verlag, Essen 2004, ISBN 3-88400-421-2
2. ↑ Volker Bialas: From the heavenly myth to the world law. A cultural history of astronomy. Ibera-Verlag, Vienna 1998
3. ↑ Clive Ruggles: Ancient Astronomy: An Encyclopedia of Cosmologies and Myth. ABC-Clio Verlag, 2005, ISBN 9781851094776 , p. 5.
4. ^ Clive Ruggles, Ancient Astronomy: An Encyclopedia of Cosmologies and Myth , p. 343f, ABC-Clio Inc., S.Barbara 2005
5. ^ On February 15, 3380 BC In the proleptic Julian calendar. There is a difference of 29 days from today's calendar, which must be deducted. Source: MPIA (U. Bastian, AM Quetz), J. Meeus: Astronomical calculations for Ephemeris Tool 4.5 .
6. ↑ Peter Kurzmann: The Neolithic Star Map of Tal-Qadi on Malta , archeology online from July 25, 2014, accessed on December 22, 2019
7. ^ ^{A b c} K. Wang, GL Siscoe: Ancient Chinese Observations . bibcode : 1980SoPh ... 66..187W
8. ^ On June 15, 763 BC In the proleptic Julian calendar. There is a difference of nine days from today's calendar, which must be deducted. See: MPIA (U. Bastian, AM Quetz); J. Meeus: Astronomical Calculations for Ephemeris Tool 4.5 .
9. ^ John North: Viewegs Geschichte der Astronomie und Kosmologie , Vieweg-Verlag 1994, p. 5
10. ↑ See also Erik Hornung : The night journey of the sun. An ancient Egyptian description of the afterlife . Patmos, Düsseldorf 2005, ISBN 3-491-69130-3
11. ↑ Gerald Avery Wainwright; B. Gunn: In: Annales du service des antiquités de l'égypte 26 (1926), pp. 160–171.
12. ↑ Abel Burja : Textbook of Astronomy (1787) p.IX
13. ↑ Ursula Seidl: The Babylonian Kudurru Reliefs: Symbols of Mesopotamian deities. Academic Press Friborg, 1989, p. 26.
14. ↑ Gottfried Gerstbach: History of Astronomy . Lecture notes, Vienna University of Technology 2010
15. ↑ F.Becker 1968, History of Astronomy , p. 14-16
16. ^ A. Aaboe: Scientific Astronomy in Antiquity. Philosophical Transactions of the Royal Society of London, Vol. 276, No. 1257, May 2, 1974 abstract , jstor.org, accessed December 19, 2011
17. ^ John M. Steele: A Brief Introduction to Astronomy in the Middle East. Saqi, London 2008, ISBN 978-0-86356-428-4 .
18. ^ TUAT , Volume 1 Old Series, Sumerian Texts .
19. ↑ The Holy Wedding , approx. 2000 BC Chr., Ritual texts, TUAT volume 2 old series, p. 659.
20. ↑ Although much Greek literature has been preserved, the amount actually brought down to modern times is probably less than 10% of all that was written . "Although much of Greek literature has been passed down, the proportion of what has actually survived into modern times is less than 10% of what has been written." (Johnson 1965). The same book received a significant change in this passage from a new author 30 years later: Why do we know so little about Greek libraries when such a relatively large amount of classic Greek literature has been preserved? It is estimated that perhaps ten percent of the major Greek classical writings have survived. “Why do we know so little about the Greek libraries when such a relatively large stock of classical Greek literature has survived? It is estimated that almost 10% of the larger Classical Greek scripts survived ”(Harris, 1995, p. 51).
21. ↑ Venus - Abend- und Morgenstern ( Memento of the original dated December 2, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , sternwarte-ehingen.de  
22. ↑ Gehler JST 1840
23. ↑ The Computer of the Ancient Greeks , Tagesspiegel, August 7, 2006, accessed January 27, 2008
24. ↑ Hipparchus as the mastermind of Ptolemy ( Memento of the original of November 22, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  
25. ↑ Hipparchus discovered the precession motion of the earth
26. ↑ Helaine Selin, et al .: Astronomy across cultures - The History of Non-Western Astronomy. Kluwer Academic Publ., Dordrecht 2000. ISBN 0792363639 .
27. ↑ Winfried Petri: Indian astronomy - their problems and charisma , Rete. Structural history of the natural sciences, Volume 1 (1972), p. 315
28. ↑ G. Gerstbach, Astronomy script, chap. 2, Vienna University of Technology 2005
29. ^ Foreign Language Press, 2005, ISBN 7-119-02664-X
30. ^ On October 22, 2137 BC In the proleptic Julian calendar. There is a difference of 19 days to the 2007 Gregorian calendar, which must be deducted. Source: MPIA U. Bastian / A. M. Quetz and J.Meeus Astronomical Calculations for Ephemeris Tool 4,5. It took place just before noon when the sun was near the scorpion's head. See also: Anton Pannekoek A History of Astronomy (literature)
31. ↑ F. Becker 1968, p. 27f
32. ↑ See BS Eastwood: Ordering the Heavens. Roman Astronomy and Cosmology in the Carolingian Renaissance. Leiden 2007.
33. ↑ It was probably carried out in Lotharingia by the unidentified astronomer , who is attested by other works .
34. ↑ F.Samhaber: The Kaiser and his astronomer. Friedrich III. and Georg von Peuerbach , Raab / Peuerbach 1999
35. ↑ Ernst Zinner's book on the history of astronomy also contains a chapter on the history of astronomy: after the Chinese and Arabs, Zinner describes the "Germanic peoples", starting here with this work by Tannstetter. See Ernst Zinner: The History of Astronomy from the First Beginnings to the Present . Berlin 1931, p. 613 f.
36. ↑ ^{a b c} From reading stone to lithium glass ( Memento from September 27, 2006 in the Internet Archive )
37. ↑ PG Bulgakov: Vklad Ibn Siny v Praktičeskuju astronomiju. In: MB Baratov u. a. (Ed.): Abu Ali Ibn Sina. K 1000-letiju so dnja roždenija. Tashkent 1980, pp. 149-157.
38. ↑ Christopher Walker: Astronomy before the telescope. British Museum Press, London 1999, ISBN 0-7141-2733-7 .
39. ^ Robert S. Westman: The Copernican Question: Prognostication, Skepticism and Celestial Order . University of California Press, Berkeley 2011. See also Thony Christie: Astronomy and Astrology: The Siamese Twins of the Evolution of Science and R. Westmann: COPERNICUS and the Astrologers
40. ↑ Text passages in Chapter 9 : “At last you will be convinced that the sun itself occupies the center of the world.” Chapter 10 “... moved around the center of the world, in which the sun also rests immovably ... but in the center of Everyone has the sun ... "
41. ↑ Doris Wolfangel: Dr. Melchior Ayrer (1520-1579). Medical dissertation Würzburg 1957, p. 36.
42. ↑ Al Sufi discovered the Andromeda nebula (M 31)
43. ↑ Arcturus , SolStation.com, accessed March 30, 2020
44. ↑ [J. Bradley: ... Account of a new discovered Motion of the Fix'd Stars , Phil. Trans. Volume 35 (1727/28), pp. 637-661, (the speed of light 8 minutes and 12 seconds, p. 653, the year of discovery being cited differently, see esp. 656-659) ( A Letter from the Reverend Mr. James Bradley Savilian Professor of Astronomy at Oxford, and FRS to Dr. Edmond Halley Astronom. Reg. & c. Giving an Account of a New Discovered Motion of the Fix'd Stars. ( Memento of the original from March 18, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note. )] 
45. ↑ ^{a b} The First Observations of Neptune , bibcode : 1997BaltA ... 6 ... 97S .
46. ↑ Flemsteed catalogs Uranus as 34 Tauri , University of Heidelberg
47. ↑ Spectroscopy - History from an Astronomical Point of View
48. ^ FU Berlin
49. ↑ Transneptune
50. ↑ Brief description of the history of Pluto's discovery
51. ↑ Elliot, Dunham and Mink discover the Uranus rings, bibcode : 1978AJ ..... 83.1240N .
52. ↑ Farewell Pioneer 10 ( Memento of the original from March 17, 2012 on WebCite ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  
53. ↑ RM Bionta et al .: Observation of a neutrino burst in coincidence with supernova 1987A in the Large Magellanic Cloud
54. ↑ Adam G. Riess, Filippenko, Challis, Clocchiatti, Diercks, Garnavich, Gilliland, Hogan, Jha, Kirshner, Leibundgut, Phillips, Reiss, Schmidt, Schommer, Smith, Spyromilio, Stubbs, Suntzeff, Tonry: Observational evidence from supernovae for an accelerating universe and a cosmological constant . In: The Astronomical Journal . 116, No. 3, 1998, pp. 1009-1038. arxiv : astro-ph / 9805201 . bibcode : 1998AJ .... 116.1009R . doi : 10.1086 / 300499 .
55. ↑ S. Perlmutter, Aldering, Goldhaber, Knop, Nugent, Castro, Deustua, Fabbro, Goobar, Groom, Hook, Kim, Kim, Lee, Nunes, Pain, Pennypacker, Quimby, Lidman, Ellis, Irwin, McMahon, Ruiz ‐ Lapuente , Walton, Schaefer, Boyle, Filippenko, Matheson, Fruchter, Panagia: Measurements of Omega and Lambda from 42 high redshift supernovae . In: The Astrophysical Journal . 517, No. 2, 1999, pp. 565-586. arxiv : astro-ph / 9812133 . bibcode : 1999ApJ ... 517..565P . doi : 10.1086 / 307221 .
56. ↑ Planck reveals an almost perfect universe. Retrieved October 9, 2013.
57. ↑ D. Charbonneau, TM Brown, RW Noyes, RL Gilliland: Detection of an Extrasolar Planet Atmosphere . In: The Astrophysical Journal . 568, 2002, pp. 377-384. arxiv : astro-ph / 0111544 . bibcode : 2002ApJ ... 568..377C . doi : 10.1086 / 338770 .