• Question: if you cant get to the center of the earth how do you know there is one

    Asked by cberry to Hitesh, Hywel, Mae, Nik, Tiffany on 13 Jun 2012.
    • Photo: Tiffany Taylor

      Tiffany Taylor answered on 13 Jun 2012:

      There are lots of things that we know even though we can’t see it. But to measure things about the centre of the earth some very clever physicists have used GPS and satellites. Don’t ask me how they did it though! I have no idea.

    • Photo: Mae Woods

      Mae Woods answered on 15 Jun 2012:

      One way to check would be to use Newtons law of gravitation. Put simply this means that every two objects will attract each other and that this attraction will depend on the mass of both the objects (how heavy they are)

      How did Newton know this I hear you ask? He made lots of experiments and found that it was always true. For over 200 years this has been tested in experiments and it always seems to work well (of course in science there are always exceptions).

      So… If we can measure the attraction to the earth by dropping an object, then we can measure how heavy the earth is. This sort of experiment was done in 1797 and is called the Cavendish experiment.

      The results of the experiment showed that the weight of the earth has a value. If there was no center of the earth, then surely we would not be able to estimate a weight.

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