• Question: was pluto once a big planet

    Asked by to Kevin on 27 Jun 2014. This question was also asked by .
    • Photo: Kevin O'Dell

      Kevin O'Dell answered on 27 Jun 2014:

      Not my area of expertise, but as I understand it Pluto has always been small. I think the idea is that when planets form around a star the middle planet (in our case Jupiter) is the biggest and the first and last planets (Mercury and Pluto) are the smallest. That’s more or less true for the planets in our solar system. There is some very clever physics behind why, but I’m not sure I understand it all!

      To me the most interesting thing about Pluto is that it has a moon, Charon, that is half its size. This means Pluto spins in quite a strange way, not round its centre but to a point between it and Charon.

Comments