• Question: We spin around the sun and the moon spins around us so why can we not feel it spinning or see the moon spinning? And why can we not see that the sun is a sphere?

    Asked by Bizarretweed to Clare, Glafkos, Paul, Samantha on 9 Mar 2015.
    • Photo: Glafkos Havariyoun

      Glafkos Havariyoun answered on 9 Mar 2015:

      Question 1: Why can we no feel the earth spinning or see the moon spinning?

      You can see the moon going around us! That is why it’s night in the US when it’s day in the UK. It’s just relatively too slow for you to see it. BUT if you put a camera on you window facing the sky and record for the whole night and then fast forward your video you will see it move and go away.

      Question 2: Why can we not see that the sun is a sphere?

      Think of a football. If I held it above my head a few meters away from you and you didn’t know what i was holding you wouldn’t tell if I was holding a ball of a piece of paper cut and coloured like a ball. You can only see a 2D version of it. But if you look at it at different angles you will see distinguish whether it’s a ball or a piece of paper.

    • Photo: Clare Devery

      Clare Devery answered on 10 Mar 2015:

      After reading the answer Glafkos gave I am fully intending to set up a ‘mooncam’. Could be a great experiment!

    • Photo: Paul Booker

      Paul Booker answered on 10 Mar 2015:

      So there are lots of questions here! And I had to check a couple of things on the internet to answer this one…

      The Earth rotates around the sun (once per year) and spins around on it’s axis (once per day).
      There is a force on us from the Earth spinning round, but compared to gravity it’s quite small, so you don’t notice it. If the Earth suddenly stopped spinning, I think (but not sure) that we would notice – but there’d be other bigger problems too.

      There is also a force on us from the Earth rotating around the sun, but it’s much smaller than the force on us from the Earth rotating! Again if we stopped going round the sun suddenly you’d feel it, but there’d be worse problems.

      You can’t really see the moon spinning without special kit. What Glafkos described below about the moon moving across the sky is actually the Earth rotating with respect to the moon. The moon rotates around the Earth and spins around it’s own axis, but because they both take about the same time (~27 days), there is a bit of the moon that we never see! (the dark side of the moon). This also makes it hard to see that the moon is actually moving.

      I think Glafkos has nailed the bit about 3D vs 2D spheres so won’t answer that bit.

    • Photo: Samantha Terry

      Samantha Terry answered on 11 Mar 2015:

      I think this questions has already been answered. Very good question though and one I had not yet considered!

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