Timeline: Science

600 BCE

Anaximander's model of the Universe

Anaximander's model of the universe tried to explain how the moon changes phases and why we can see the stars when it's dark.

400 BCE

Aristotle's model of the Universe

Aristotle's model of the universe showed the planets and sun rotating around the earth with the stars in fixed positions, but it did not explain how mercury and mars retrograded, as it was not accurate.

150

Ptolemy proposed ‘epicycles’ to explain planetary motion

Ptolemy solved the problem with Aristotle's model by having the planets orbit in small circles while orbiting around the earth. This model was used for a long time.

1543

Copernicus hypothesized the heliocentric model

Copernicus was a polish astronomer who first suggested a heliocentric model, a model in which the sun is in the middle.

1608

Invention of telescope

Period: 1609 to 1618

Kepler develops his laws of planetary motion

Jan 7, 1610

Galileo is first to use telescope to look at the night sky; discovery of 4 moons of Jupiter

1687

Newton’s Laws of Universal Gravitation

Mar 13, 1781

Herschel is first to discover a planet using a telescope (Uranus)

Jun 20, 1944

First spaceflight in history

Oct 24, 1946

First photograph of Earth from space

Feb 20, 1947

First animals in space (fruit flies)

Jun 14, 1949

First mammal in space

Oct 4, 1957

First artificial satellite

Nov 3, 1957

First mammal in orbit

Aug 19, 1960

First plants and animals to return alive from Earth orbit

Apr 12, 1961

First human spaceflight

Jul 14, 1965

First photographs of another planet from space

Jul 16, 1969

First human flight to another celestial body: the moon

Jul 24, 1969

First human on another celestial body: the moon

May 19, 1971

First space station

Sep 5, 1977

Voyager 1 launched

Apr 24, 1990

Hubble Space Telescope launched

Nov 20, 1998

International Space Station launched

Aug 25, 2012

First spacecraft to go beyond all planets in the solar system