Cosmology - Timeline

Planet-sized object Eris, Haumea and Makemake are discovered in the Kuiper Belt.

Arno Penzias and Robert Wilson discover cosmic microwave background radiation, further evidence supporting the Big Bang model.

Edwin Hubble discovers evidence of an expanding universe, which supports the Big Bang model.

Georges Lemaitre proposes the Big Bang theory, which suggests that the universe began as a giant explosion of energy.

Ernst Opik demonstrates that the Andromeda nebula lies outside the Milky Way galaxy.

Friedrich Bassel observes stellar parallex-the apparent movement of stars due to the Earth's movement around the Sun.

William Herschel constructs the first map of the Milky Way galaxy.

Thomas Wright suggests that the milky way galaxy is a flattened disk of stars and that nebulae might be other galaxies.

Galileo publishes his Dialogue on Two World Systems, which argues in favour of the heliocentric model of the universe.

Ferdinand Magellan is the first European to observe the Magellanic Clouds, which are later recognised as galaxies outside the Milky Way.