• Question: why is the earth round?

    Asked by jadoolan to Damien, Rachael, Simon, Suzi, Tim on 19 Jun 2011.
    • Photo: Suzi Gage

      Suzi Gage answered on 16 Jun 2011:

      Hi @jadoolan
      I think this is because gravity is working on the earth, pulling it towards itself, which makes it spherical.

      I think…

      🙂

    • Photo: Tim Fosker

      Tim Fosker answered on 17 Jun 2011:

      Hi @jadoolan

      As @Suzi said the earth is round because gravity works on the earth pulling it inwards. The greater the mass of an object the more this will happen, so an asteroid which has a much smaller mass than the earth will be very lumpy. The earth is lumpy with mountains, hills and valleys, but a neutron star which has a very high mass will be an almost perfectly smooth sphere.

    • Photo: Damien Hall

      Damien Hall answered on 19 Jun 2011:

      I think it’s also true that the Earth (and other planets) are actually not quite round (I mean apart from the mountains and valleys). There’s a very, very slight bulge at the Equator, which happens because of the Earth’s spin creating a force which throws things outwards from it (called centrifugal force). Like gravity, this force acts more strongly the more it has to act on, so, as the distance from the centre axis of the Earth to its surface is greatest at the Equator, the centrifugal force is greatest there – and the Equator gets pushed out a bit. The result is that the Earth isn’t quite spherical, but shaped a bit like a rugby ball (not as extremely oval as that, though). There are more details here:

      http://en.wikipedia.org/wiki/Earth%27s_rotation#Physical_effects

      Hope that’s interesting!

Comments