Events
Aristotle describes
the geocentric
(Earth-centred)
model of the
universe
(350 BC)Aristarchus proposes
a heliocentric
(Sun-centred)
model of the
universe
(250 BC)Ferdinand Magellan
was the first European
to observe the Magellanic
Clouds later known as other
galaxies
(1520)Nicholas Copernicus
published paper that
presents a heliocentric
model with improvements
to Aristarchuses
(1543)Kelper published
Astronomia Nova
which explained the
motion of planets
using the heliocentric
model
(1609)Galileo publishes Dialogue
on Two World Systems which
argues the heliocentric model
(1632)Thomas Wright suggested
the Milky Way is a flattened
disk of stars and other nebulae
might be other galaxies
(1750)Ernst Opik demonstrates
the Andromeda nebulae
is outside the Milky Way
(1922)Georges Lemaitre proposed
the Big Bang theory suggesting
the universe began as a giant
explosion
(1927)Edwin Hubble discovers
evidence of an expanding
universe supporting the
Big Bang theory
(1929)
Comments