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== Pluto's Origin ==

== Pluto's Origin ==

Pluto was initially supposed to have been a [[moon]] of [[Neptune]]<ref>http://www.britannica.com/eb/article-54312/Pluto</ref>. But with the discovery of [[Charon]] in 1978, and the subsequent discoveries of its other moons [[Hydra (moon)|Hydra]] and [[Nix]], that theory became far less plausible.

Pluto was initially supposed to have been a [[moon]] of [[Neptune]]. But with the discovery of [[Charon]] in 1978, and the subsequent discoveries of its other moons [[Hydra (moon)|Hydra]] and [[Nix]], that theory became far less plausible. The current theory is that Pluto and Charon both formed from the solar nebula as the other planets in the solar system did. <ref>http://www.britannica.com/eb/article-54312/Pluto</ref>

 

Another hypothesis has held that Pluto entered the [[solar system]] from outside, and the [[Sun]] captured it. But if such a mass dived into the solar system from outside, then it would have followed a hyperbolic path. That it did not pass back ''out'' of the solar system to complete the hyperbola begs explanation.

== In popular fiction ==

== In popular fiction ==