| 2500 BC |
Stonehenge is used to predict eclipses of the
Moon. |
| 1800 - 400 BC |
The Babylonians develop the first calendar based on
the motion of the Sun and the phases of theMoon. |
| 165 BC |
Chinese astronomers record the first sunspots. |
| 46 BC |
The Julian calendar is brought
into use in the Roman Empire by Julius Caesar. |
| 635 AD |
A Chinese scholar
discovers that the tail of a comet always points away from the Sun. |
| 1054 AD |
Chinese astronomers
witness the supernova
explosion that creates the Crab nebula. |
| 1066 AD |
A large comet,
now known as Halley's Comet, is first seen. |
| 1350 AD |
Jean Buridan develops
the idea of "impetus," now known as inertia. |
| 1500s AD |
The first reflecting
telescope is developed by Leonard Digges. |
