• Question: What is the difference between a asteriod and a comet?

    Asked by 10doherg to Adam, Catherine, Leila on 22 Mar 2012.
    • Photo: Leila Battison

      Leila Battison answered on 22 Mar 2012:

      Comets have a small nucleus and then a thick coating of ice, which is ionised when it comes close to the sun to make the tail that you can see behind them in the sky. They are though to have formed far away from the sun in the outer solar system.

      Asteroids are made of rock and metal, and are usually concentrated in big belts in circular orbits. They aren’t very reflective, so aren’t easy to spot without a telescope. They are thought to have formed in the closer to the sun where it was hotter.

    • Photo: Adam Stevens

      Adam Stevens answered on 22 Mar 2012:

      Asteroid are big balls of rock leftover from when the planets were being formed. They are made up of the original stuff of the solar system and most of them orbit in between Mars and Jupiter. Asteroids typically have fairly standard orbits, mostly about circular.

      Comets are balls of ice and dust that was leftover right at the edges of the solar system. They tend to orbit further out, past the Kuiper belt, and normally have very elliptical orbits, so they go very very very far from the sun, takes ages to move around and then start speeding up as they move in quite close to the sun, then go very far away again. This is why there are a lot of comets (like Halley’s Comet) that we see every few hundred years or so.

      So asteroids are rock and tend to be in the middle of the solar system and comets are mostly ice and orbit very far out on non-circular orbits.

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