Astronomers are still arguing whether the recently discovered "10th planet" in our Solar System - Sedna - should be included in the list.
Tolkien fans want to call it Shadowfax - after Gandalf's horse.
But what does look likely is that our Moon will get a new name too.
"After years of just being called Moon, we thought it would good to give it a proper name - so we've chosen Gollum," said Prof Polorf.
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Rings quiz - Wizards
