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Before 1600
The known Universe
consists of only 8
bodies:
Earth, Sun, Moon,
Mercury, Venus, Mars,
Jupiter, Saturn.
Earth is thought to
be the centre of the
Universe with all
other bodies orbiting
it. (Ptolemaic
system)
Development of the Copernican
system:
Problem with the Ptolemaic Universe – some
of the planets seem to move in the wrong
direction in the sky.
Can only be explained if the Earth and
the other planets orbit the Sun –
Copernican theory
The Discovery of Uranus
1781 – William Herschel
During sky survey spotted a
faint star that appeared
disc like in the
constellation of Gemini
(near the ecliptic). Further
observations revealed its
motion and orbit.
The Discovery of Neptune
1846 – Peturbations in Uranus' orbit
suggests another planet lies beyond
Uranus.
Adams and Le Verrier predict an orbit and
a search conducted by Encke discovers the
new planet at the predicted location.
The Discovery of Pluto
Further peturbations in
Uranus' orbit measured
by Percival Lowell and
Edward Pickering
suggests another the
existence of another
mysterious planet.
American student Clyde
Tombaugh eventually
discovers Pluto in a
photograph in 1930.