This is a timeline of astronomy. It covers ancient, medieval, Renaissance-era, and finally modern astronomy.
Prehistoric Period
7500 BCE
Neolithic inhabitants constructed Nabta Playa megalithic structures, in Aswan located in Upper Egypt. These structures served to coordinate astronomical observations, religious practices and alignment with solar patterns and annual flooding cycles. These practices have been linked with the emergence of cosmology in Old Kingdom Egypt.
Antiquity
750 BC Mayan astronomers discover an 18.7-year cycle in the rising and setting of the Moon. From this they created the first almanacs – tables of the movements of the Sun, Moon, and planets for the use in astrology. In 6th century BC Greece, this was also discovered.
585 BC Thales of Miletus is said to have predicted a Eclipse of Thales solar eclipse that occurred in 585 BC.
467 BC Anaxagoras produced a correct explanation for eclipses and then described the Sun as a fiery mass larger than the Peloponnese, as well as attempting to explain rainbows and meteors. He was the first to explain that the Moon shines due to reflected light from the Sun.Burnet J. (1892) Early Greek Philosophy A. & C. Black, London, OCLC 4365382, and subsequent editions, 2003 edition published by Kessinger, Whitefish, Montana,
400 BC Around this date, Babylonians use the zodiac to divide the heavens sexagesimally into twelve equal segments of thirty degrees each, the better to record and communicate information about the position of celestial bodies.
387 BC Plato, a Greek philosopher, founds a school (the Platonic Academy) that will influence the next 2000 years. Borrowing and expanding from Pythagoreanism, it promotes the idea that everything in the universe moves in harmony and that the Sun, Moon, and planets move around Earth in perfect circles.Australia Telescope National Facility. Classical Astronomy. https://web.archive.org/web/20140314115151/http://www.atnf.csiro.au/outreach//education/senior/cosmicengine/classicalastronomy.html
380 BC Aristotle, a Greek polymath, described motion of physical objects based on their affinity with one of four classical elements: earth, water, air, or fire.
350 BC The astronomer Shi Shen is believed to have cataloged 809 stars in 122 constellations, and he also made the earliest known observation of sunspots.Temple, R.(1988). The Observation of sunspots. The UNESCO Courier. XLI,10. Retrieved from https://unesdoc.unesco.org/ark:/48223/pf0000081672
270 BC Aristarchus of Samos proposed the first known model of heliocentrism, in which Earth rotates on its axis and revolves around the Sun.
240 BC The earliest recorded sighting of Halley's Comet is made by Chinese astronomers. Their records of the comet's movement allow astronomers today to predict accurately how the comet's orbit changes over the centuries.
170 BC Hipparchus incidentally discovered of the precession of the equinoxes.
70 BC Vitruvius explains that an object's fall speed depends on their specific gravity.
AD 140
Ptolemy presented a geocentric model in the Almagest, placing Earth at the center with the planets and other celestial objects orbiting it.
Middle ages
AD 400 The Hindu cosmological time cycles explained in the Surya Siddhanta, give the average length of the sidereal year (the length of the Earth's revolution around the Sun) as 365.2563627 days, which is only 1.4 seconds longer than the modern value of 365.256363004 days. This remains the most accurate estimate for the length of the sidereal year anywhere in the world for over a thousand years.
AD 499 Indian mathematician-astronomer Aryabhata, in his Aryabhatiya, first explains the elliptical model of the planets, where the planets spin on their axis and follow elliptical orbits, the Sun and the Moon revolve around the Earth in epicycles. He also writes that the planets and the Moon do not have their own light but reflect the light of the Sun and that the Earth rotates on its axis causing day and night and also that the Sun rotates around the Earth causing years.*
AD 628 Indian mathematician-astronomer Brahmagupta, in his Brāhmasphuṭasiddhānta, first recognizes gravity as a force of attraction. He gives methods for calculations of the motions and places of various planets, their rising and setting, conjunctions, and calculations of the solar and lunar eclipses.
AD 773 The Sanskrit works of Aryabhata and Brahmagupta, along with the Sanskrit text Surya Siddhanta, are translated into Arabic, introducing Arabic astronomers to Indian astronomy.
AD 777 Muḥammad ibn Ibrāhīm al-Fazārī and Yaʿqūb ibn Ṭāriq translate the Surya Siddhanta and Brahmasphutasiddhanta, and compile them as the Zij al-Sindhind, the first Zij treatise.
AD 830 The first major Arabic work of astronomy is the Zij al-Sindh by Muhammad ibn Musa al-Khwarizmi. The work contains tables for the movements of the Sun, the Moon, and the five planets known at the time. The work is significant as it introduced Ptolemaic concepts into Islamic sciences. This work also marks the turning point in Arabic astronomy. Hitherto, Arabic astronomers had adopted a primarily research approach to the field, translating works of others and learning already discovered knowledge. Al-Khwarizmi's work marked the beginning of nontraditional methods of study and calculations.Dallal (1999), pg. 163
AD 850 al-Farghani wrote Kitab fi Jawani ("A compendium of the science of stars"). The book primarily gave a summary of Ptolemic cosmography. However, it also corrected Ptolemy based on findings of earlier Arab astronomers. Al-Farghani gave revised values for the obliquity of the ecliptic, the precessional movement of the apogees of the Sun and the Moon, and the circumference of the Earth. The books were widely circulated through the Muslim world and even translated into Latin.Dallal (1999), pg. 164
AD 928 The earliest surviving astrolabe is constructed by astronomer Nastulus.
AD 1030 Al-Biruni discussed the Indian geocentric theories of Aryabhata, Brahmagupta and Varāhamihira in his Ta'rikh al-Hind (Indica in Latin). Biruni stated that the followers of Aryabhata consider the Earth to be at the center. In fact, Biruni casually stated that this does not create any mathematical problems.Saliba (1999).
AD 1031 Al-Sijzi, a contemporary of Al-Biruni, defended the theory that Earth rotates on its axis.
AD 1054 Chinese astronomers record the sudden appearance of a bright star. Native-American rock carvings also show the brilliant star close to the Moon. This star is the Crab supernova exploding.
AD 1070 Abu Ubayd al-Juzjani published the Tarik al-Aflak. In his work, he indicated the so-called "equant" problem of the Ptolemic model. Al-Juzjani even proposed a solution to the problem. In al-Andalus, the anonymous work al-Istidrak ala Batlamyus (meaning "Recapitulation regarding Ptolemy"), included a list of objections to the Ptolemic astronomy.
One of the most important works in the period was Al-Shukuk ala Batlamyus ("Doubts on Ptolemy"). In this, the author summed up the inconsistencies of the Ptolemic models. Many astronomers took up the challenge posed in this work, namely to develop alternate models that evaded such errors.
AD 1126 Islamic and Indian astronomical works (including Aryabhatiya and Brahma-Sphuta-Siddhanta) are translated into Latin in Córdoba, Spain in 1126, introducing European astronomers to Islamic and Indian astronomy.
AD 1150 Indian mathematician-astronomer Bhāskara II, in his Siddhanta Shiromani, calculates the longitudes and latitudes of the planets, lunar and solar eclipses, risings and settings, the Moon's lunar crescent, syzygies, and conjunctions of the planets with each other and with the fixed stars, and explains the three problems of diurnal rotation. He also calculates the planetary mean motion, ellipses, first visibilities of the planets, the lunar crescent, the seasons, and the length of the Earth's revolution around the Sun to 9 decimal places.
AD 1190 Nur ad-Din al-Bitruji proposed an alternative geocentric system to Ptolemy's. He also declared the Ptolemaic system as mathematical, and not physical. His alternative system spread through most of Europe during the 13th century, with debates and refutations of his ideas continued to the 16th century. (PDF version)
AD 1250 Mu'ayyad al-Din al-Urdi develops the Urdi lemma, which is later used in the Copernican heliocentric model.
Nasir al-Din al-Tusi resolved significant problems in the Ptolemaic system by developing the Tusi-couple as an alternative to the physically problematic equant introduced by Ptolemy.M. Gill (2005). Was Muslim Astronomy the Harbinger of Copernicanism? His Tusi-couple is later used in the Copernican model.
Tusi's student Qutb al-Din al-Shirazi, in his The Limit of Accomplishment concerning Knowledge of the Heavens, discusses the possibility of heliocentrism.
Najm al-Din al-Qazwini al-Katibi, who also worked at the Maraghah observatory, in his Hikmat al-'Ain, wrote an argument for a heliocentric model, though he later abandoned the idea.
AD 1350 Ibn al-Shatir (1304–1375), in his A Final Inquiry Concerning the Rectification of Planetary Theory, eliminated the need for an equant by introducing an extra epicycle, departing from the Ptolemaic system in a way very similar to what Copernicus later also did. Ibn al-Shatir proposed a system that was only approximately geocentric, rather than exactly so, having demonstrated trigonometrically that the Earth was not the exact center of the universe. His rectification is later used in the Copernican model.
Renaissance and Age of Enlightenment
16th century
AD 1500 Nilakantha Somayaji proposes a model very similar to the Tychonic system. His equation for the center for the planets Mercury and Venus were the most accurate until Johannes Kepler
AD 1543 Nicolaus Copernicus publishes De revolutionibus orbium coelestium containing his theory that Earth travels around the Sun. However, he complicates his theory by retaining Plato's perfect circular orbits of the planets.
AD 1572 A brilliant supernova (SN 1572 – thought at the time to be a comet) is observed by Tycho Brahe, who proves that it is traveling beyond Earth's atmosphere and therefore provides the first evidence that the heavens can change.
17th century
AD 1608 Dutch eyeglass maker Hans Lippershey tries to patent a refracting telescope (the first historical record of one). The invention spreads rapidly across Europe, as scientists make their own instruments. Their discoveries begin a revolution in astronomy.
AD 1609 Johannes Kepler publishes his New Astronomy. In this and later works, he announces his three laws of planetary motion, replacing the circular orbits of Plato with elliptical ones. Almanacs based on Johannes' laws prove to be highly accurate.
AD 1610 Galileo Galilei publishes Sidereus Nuncius describing the findings of his observations with the telescope he built. These include spots on the Sun, craters on the Moon, and four satellites of Jupiter. Proving that not everything orbits Earth, he promotes the Copernican view of a Sun-centered universe.
AD 1655 As the power and the quality of the telescopes increase, Christiaan Huygens studies Saturn and discovers its largest satellite, Titan. He also explains Saturn's appearance, suggesting the planet is surrounded by a thin ring.
AD 1663 Scottish astronomer James Gregory describes his "gregorian" reflecting telescope, using parabolic mirrors instead of lenses to reduce chromatic aberration and spherical aberration, but is unable to build one.
AD 1668 Isaac Newton builds the first reflecting telescope, his Newtonian telescope.
AD 1687