Astronomy Discovery Timeline

Events

Eratosthenes

180 B.C.

First good size measurement of Earth

Claudius Ptolemy

140 AD

Almagest Theory (geocentric model)

Nicolaus Copernicus

1510

Heliocentric Theory

Johannes Kepler

1610

The planets travel around the sun in elliptical fashion

Galileo Galilei

1613

Copernican Theory ( supports heliocentric model)

Giovanni Cassini

1675

Cassini Division (gaps in Saturn's Rings)

Isaac Newton

1687

Law of Universal Gravitation

Edmund Halley

1705

Halleys Comet

William Herschel

1781

Discovers Uranus

Edwin Hubble

1929

Discovers The Cosmos

Clyde Tombaugh

1930

Discovers Pluto

Stephen Hawking

1970

Black Holes and Quantum Theory