Why was Pluto classified as a dwarf planet?

Answer 1

Pluto was deemed a planet when it was discovered by US astronomer Clyde Tombaugh in 1930. It retained the status of a planet until it was re-classified as a dwarf planet on August 24th 2006 by the International Astronomical Union (IAU).

As other large objects had been discovered orbiting the Sun, controversy had developed about what should be considered a planet. A new definition for a planet was established and Pluto did not fit the new criteria, so was deemed a dwarf planet. There are 5 known dwarf planets (Eris discovered in 2005 is slightly larger than Pluto) and expectations that many more will be found. Dwarf planets are spherical in shape and orbit the sun directly, but not dominating its orbit like all 8 remaining planets.

Answer 2

Pluto was reclassified as a dwarf planet for a number of reasons. In 2006, the International Astronomical Union (IAU) passed two different resolutions, one of which defined what a planet is. This definition is as follows:

Resolution 5A - Definition of a planet:

A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood [sic] around its orbit.

Unfortunately, Pluto does not fulfill part (c) of this definition. This is because it's orbit crosses paths with that of Neptune (which is why sometimes Neptune is further from the sun than Pluto).

Answer 3

Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union due to its small size, its inability to clear its orbit of debris like a regular planet, and its orbit that overlaps with Neptune's. This decision was made to establish criteria that distinguishes planets from other celestial bodies, resulting in the creation of a new category for Pluto and similar objects.

Answer 4

2006 I think.............