• Question: How do you measure the distance from us to the sun

    Asked by beccapops to Kate on 11 Mar 2014.
    • Photo: Kate Salmon

      Kate Salmon answered on 11 Mar 2014:

      Hi @beccapops this is a very good question! Basically, scientists use trigonometry which I’m not sure you will have done at school yet (you will do eventually). It involves creating a triangle between the sun and one other object (such as another planet e.g. Venus).

      1. Now imagine that the earth is set at one position in its orbit, as Venus travels along its orbit there are two points where the Venus-Sun line and the Earth-Sun are 90 degrees apart.
      1. At this point, we can work out the distance from us to Venus using a radar beam which bounces back off Venus back to us. The time is takes to come back can help us work out the distance between us and Venus.
      3. Then we can use trigonometry (from knowing the angle and distance) to work out the other side of the triangle which is from us to the sun.

      The actual distance to the sun is 92,955,830 miles!

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