• On 2300 BC, Chinese Astronomers observed the sky.
• A comet was sighted for the first time in 2296 BC by the Chinese. 

1. The Stonehenge was constructed in 1860 BC on the Salisbury Plain in Southern England.
2. Babylonians began to keep astronomical observational records in 1800 BC.
3. Chaldean astronomers of Mesopotamia in 1600BC identify the zodiac.
4. Solar eclipse observed and recorded by Babylonians in 763BC.
5. The son of Examyes and Cleobuline, Thales of Miletus a pre-Socratic philosopher, was born in the city of Miletus, an ancient Greek Ionian city on the western cost of Asia Minor, in 624BC.
6. The great philosopher and a scientist, Thales of Miletus predicted a solar eclipse on May 28, 585 BC.
7. Thales died in Miletus, Asia Minor in 547BC. .
8. In 500 BC Pythagoras suggests that the Earth is a sphere and not flat, as had been previously assumed
9. Greek philosopher Leucippus and Democritus, his student present the concept that all matter consists of fundamental particles called atoms in 440 BC. (Atom comes from the Greek word meaning "indivisible.")
10.  Chinese spot first moons of Jupiter in 365BC with the naked eye.
11. In 350 BC, Aristotle writes Meteorological, the first book on weather.
12. Euclid, a Greek from Alexandria, writes Elements, introducing geometry (which means "land measurement") in 300 BC.
13.  Aristarchus says that the Sun is at the center of the Solar System; this is generally dismissed in 270BC.
14.   What would later become known as Halley’s comet is observed by the Chinese in 240BC.
15. Archimedes calculates the area of circle, defines the principles of the lever, the screw, and buoyancy in 212 BC.
16.  Eratosthenes calculates the size of Earth in 194 BC.
17. Hipparchus of Rhodes (161 BC-122 BC,) Defines the cosmos by latitude and longitude; and makes triangular measurement of celestial navigation in 120 BC..
18. Alexandrian astronomer and mathematician Ptolemy (Claudius Ptolemaeus) publishes Almagest, in which he catalogued 1,022 stars - the previous known number of stars being 850. This was the primary astronomy text for 14 centuries in 127.
19. Nicolas Copernicus was born in Poland in 1473.
20. Astronomer Nicolas Copernicus suggests that the earth moves around the sun in 1514.
21. In 1543, Copernicus publishes “De Revolutionibus Orbium Caoelestium” which means (The Revolutions of the Heavenly Spheres), the theory that earth revolves around the sun, while on his deathbed.
22. Tycho Brahe was born in Denmark in 1546.
23.  Books on Geography and Astronomy are burned in England because people thought they contained magic in 1552.
24. Galileo Galilei was born in Italy in in 1564.
25. Tycho Brahe observes a supernova in Cassiopeia constellation in 1572.
26. Galileo Galilei demonstrates that successive beats of a pendulum always take place in the same length of time, regardless of the distance through which it swings in 1583.
27. Microscope invented by Dutch spectacle maker Zacharias Janssen in 1590.
28. Galileo Galilei experiments with falling objects.
29. Galileo Galilei in 1593 invents a water thermometer.
30. Johannes Kepler publishes Mysterium cosmographicum in 1596.
31. Tycho Brahe in 1598 describes his experiments in astronomy.
32. In 1608, Hans Lippershey invents the telescope.
33. Galileo Galilei improves the telescope in 1609.

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