Around 4000 (?) B.C.
The oldest astronomical observation ever recorded (Egypt and Central America)
Around 3000 B.C.
The first written materials on astronomy (Egypt, China, Mesopotamia and Central America)
2697 B.C.
The oldest preserved relation on the Sun eclipse (China)
Around 2000 B.C.
The first solar-lunar calendars in Egypt and Mesopotamia.
Stonehenge Sanctuary (England).
Constellations first drawn up by the ancient astronomers.
6th century B.C.
Pythagoras and Thales of Miletus speculate that the Earth is a sphere.
Around 330 B.C.
Aristotle's On Heavens
Around 280 B.C.
Aristrachus of Samos suggests that the Earth revolves about the Sun (heliocentric concept of the Universe). He also provides the first estimations on Earth-Sun distance
Around 240 B.C.
Eratosthenes of Cyrene (now Shahhat, Libya) measures the circumference of the earth with extraordinary accuracy by determining astronomically the difference in latitude between the cities of Syene (now Aswan) and Alexandria, Egypt
Around 130 B.C.
Hipparchus discovers the precession of the equinoxes and develops the first star catalog and charts ( around 1000 bright stars)
45 B.C.
The introduction of Julian calendar ( purely solar calendar) to the Roman Empire upon the advice of the Greek astronomer Sosigenes
Around A.D. 140
Ptolemy suggests the geocentric theory of the Universe in his famous work Mathematike Syntaxis widely recognized from its Arabic translation as Almagest
5th Century: Collapse of Roman Empire
IX-XI century A.D.
Intensive development of Arabic and Persian astronomy (star charts and catalogs, planets and the Moon movement, better estimations of the Earth size, and calendar improvement)
A.D. 813
Al Mamon founds the Bagdad school of astronomy. Mathematike Syntaxis by Ptolemy is translated into Arabic as al-Majisti (Great Work) later called by Latin scholars Almagest
A.D. 903
Al-Sufi draws up his star catalog
1054
Chinese astronomers observe supernova in Taurus (now this supernova remnant is known as the Crab Nebula (M1)