posted on Aug, 31 2011 @ 02:25 PM
Originally posted by Suspiria
We've known about Eris for a while..
Poor Pluto lost it's status over the new discoveries.
It was the discovery of Eris that directly
led to the creation of the classification "Dwarf Planet", and the demotion of Pluto to that new
category of heavenly bodies.
Someone above said Eris is smaller than Pluto, but it is actually larger than Pluto -- and Eris has its own Moon. When Eris was discovered, it was
considered to be the 10th planet -- at least some thought there was a good argument for it being considered a planet. The simplified
version of the argument was that if it was bigger than Pluto, and Pluto was a planet, then Eris perhaps should be a planet, also.
However, instead of calling Eris the 10th planet, the International Astronomical Union decided to create that new category called Dwarf Planets, and
put BOTH Pluto and Eris in that category -- a category that (as of this writing) also includes Ceres, Orcus, Haumea, Quaoar, Makemake, 2007 OR10, and
So now there are eight known planets and nine known dwarf planets (but there are probably more undiscovered dwarf planets). Who knows -- there may be
another planet-sized body out there beyond Eris, such as "Tyche", which is hypothesized to exist, although only through very indirect evidence.
edit on 8/31/2011 by Soylent Green Is People because: (no reason given)