• Question: what have you learnt about the comits and asteroids orbiting our sun

    Asked by coolthew to Alan on 10 Mar 2014.
    • Photo: Alan Fitzsimmons

      Alan Fitzsimmons answered on 10 Mar 2014:

      We know that comets are made of different types of ice and are very old. I was one of the first astronomer to see where they come from, in a belt of comets further away than the planet Neptune.

      I was also one of the astronomers that discovered that comets have 3 types of tails, not just the two types that everyone knew about before.

      Asteroids are also very old, but are mostly made of rock. I helped show that when we measure the type of rock they are made of using telescopes, it’s the same as when we look at meteorites on the ground.

      Asteroids also spin. The Earth spins once every 24 hours, which is the length of our day. Days on asteroids can be much shorter, 8 hours or less. That would mean the sun rises and sets every 8 hours.

      I once measured an asteroid whose day only lasts 12 minutes! Not only that, our team found that it was getting even faster!

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