Changes

== The dwarf planet controversy ==

== The dwarf planet controversy ==

[[Image:Pluto3.gif|left|thumb|Pluto(center) with moon [[Charon]]. NASA image]]

[[Image:Pluto3.gif|left|thumb|Pluto(center) with moon [[Charon]]. NASA image]]

The discovery of [[Eris]], a scatter-disk body 27% more massive than Pluto, caused a controversy concerning what does, and what does not, constitute a [[planet]]. If Pluto were to retain its historical designation of "planet," then Eris would also qualify. But Eris was held not to qualify because it was in a neighborhood with multiple other objects, a situation similar to those of similar bodies in the [[asteroid]] belt, namely [[Ceres]] and [[Eros]].

The discovery of [[Eris]], a scatter-disk body 27% more massive than Pluto, caused a controversy concerning what does, and what does not, constitute a [[planet]]. If Pluto were to retain its historical designation of "planet," then Eris would also qualify. But Eris was held not to qualify because it was in a neighborhood with multiple other objects, a situation similar to those of similar bodies in the [[asteroid]] belt, namely [[Ceres]] and [[Eris]].

In 2006, the [[International Astronomical Union]] passed the following resolution:{{cquote|'''RESOLUTION 5A'''

In 2006, the [[International Astronomical Union]] passed the following resolution:{{cquote|'''RESOLUTION 5A'''

Brown suspects the IAU wanted to demote Pluto, because Pluto violates, by its very existence, every conventional theory of planetary origin.

Brown suspects the IAU wanted to demote Pluto, because Pluto violates, by its very existence, every conventional theory of planetary origin.

== Orbital characteristics ==

== Orbital characteristics ==