• Question: at a time was there more planets in our solar system be4

    Asked by riob88 to Davie, Gemma, James P, James V, Nuala on 2 Jul 2012.
    • Photo: James Verdon

      James Verdon answered on 2 Jul 2012:

      Hi riob,

      When the solar system initially formed from the debris surrounding our sun, after the sun formed, then there would have been lots of small asteroids and planetoids. I’m not sure you would call any of them planets though. Gradually, they all collided together to become the planets we know today. Some people suggest that there may have been another planet in between Mars and Jupiter, where the asteroid belt is now, and that the planet disintegrated to form the asteroids. I’m not sure if that’s true or not.

      We used to call Pluto a planet. However, we realised that there are a number of other bodies of similar size to Pluto orbiting at the edge of our solar system. Therefore, if we were to call Pluto a planet, we’d have to call all these other things planets as well. Instead, we decided that we wouldn’t call Pluto a planet anymore.

    • Photo: James Pope

      James Pope answered on 2 Jul 2012:

      Hi riob88,

      Since all the Planets finished forming we have had just the 8 planets in our solar system. I remember when I was younger and Pluto was a planet, there was talk of Planet X (or 10), but nothing of suitable size was found and I think this played a role in declassifying Pluto from a planet.

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