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A ninth planet is theorized to exist
Percival Lowell theorized that a ninth planet existed because he noticed that Uranus and Neptune wobbled at some points in their orbit around the sun. Lowell theorized that this was due to a planet's gravitational pull on the planet. -
Period: to
Pluto, discovered and disowned
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Pluto discovered
Pluto was discovered by Clyde Tombaugh at the Lowell Observatory in Flagstaff, AZ. -
Pluto's Birthday
Using a new technique-- photographic plates combined with a blink microscope--Pluto's existence was confirmed and announced to the public on this date. -
Pluto investigated
James Christy and Robert Harrington discovered Pluto’s only known moon, Charon -
Pluto Demoted
Pluto is no longer a planet. This was decided in 2006 by the National Astronomical Union -
Pluto: Dwarf or Giant?
Pluto was declared a dwarf planet because its small size. However, as a member of the Kupier Belt, it is a giant compared to the other rocks.
