Why is there only 8 planets now

  • Thread starter poppop24
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  • #1
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Main Question or Discussion Point

Please explain why there is no pluto any more:surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised :surprised
 

Answers and Replies

  • #2
chroot
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The International Astronomical Union recently changed the official definition of "planet." Pluto does not meet this new definition. Pluto still exists, but it is no longer considered a planet.

- Warren
 
  • #4
EL
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The alternatives were (basically) to include three new planets, or take away Pluto, and the later was chosen...
 
  • #5
LURCH
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I doubt it will last for long, though. The new definition is very sketchy, and depends upon a body having "cleared out" the immediate vicinity of its orbit. Pluto was not disqualified because of its size, or the eccentricity of its ellipse, or its inclination to the orbital plane, but because it crosses Neptune's orbital radius. By this definition, Neptune (having failed to "clear out" Pluto from its orbit) should also be disqualified.

In fact, because there are still thousands of NEO's whizzing about the inner solar system, many of them crossing inside the orbit of Venus, the new definition may reduce the entire solar system to only one planet: Mercury!
 
  • #6
SpaceTiger
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