Two years after being demoted to the status of "interesting asteroid" Pluto may regain the title of planet after a fourth moon was found orbiting the distant object.
Pluto was not spotted until 1921, and was thought to be planet sized due to it's distance and brightness.
In the 1980s, somebody thought to have another look at Pluto with a better telescope and discovered it wasn't one planet, but two. After a bit of discussion, they named the smaller of the two planets Charon, and the larger of the two continued to be named after Disney's dog.
"Our excuse is that Pluto is a long way away," said Professor Brian Cox. "And cosmologists like using the big telescopes to look at things even further away, so looking at Pluto tends to be low on the list of priorities."
Excuses or not, it took another fifteen years before anybody thought to think about Pluto again, and it was not in Pluto's favour this time.
"Because Charon doesn't really orbit Pluto," said Cox, "they orbit each other, astronomers decided Pluto couldn't be a planet."
This annoyed a lot of astronomers, who grew up with nine planets, and they've been searching for reasons to make Pluto a planet again. Very quickly, a third moon was found, but it orbited Pluto AND Charon.
"That was quite interesting," said Cox. "A little unusual, and in our own solar system. But it didn't make Pluto a planet."
The third moon still doesn't have a name, but will soon after the next meeting of the International Astronomy Union. To throw a spanner in the works ahead of their next meeting, a fourth moon has been found this week, and this one does orbit Pluto, although it's orbit is a little complicated.
"It does orbit Pluto. But it also orbit's Charon. And sometimes both of them," said Cox. "We think at times it may orbit neither of them. What the IAU make of that, we'll have to wait and see."
It is expected that those who like order, simplicity and weak tea, will claim that Pluto is still not a planet, and those that like interesting, complicated and mint juleps will have to keep looking for a way to return the Solar System back to nine planets.