• Question: Do you think the celestial theory is an appropriate and practical tool to successfuly study spherical astronomy?

    Asked by matthiasspicer to Ellie on 2 Jul 2012.
    • Photo: Eleanor Turpin

      Eleanor Turpin answered on 2 Jul 2012:

      Hi matthiasspicer,

      Thanks for your question but to be honest I’ve not heard of celestial theory. Can you tell me more about it. Perhaps you’re thinking of something I call a different name

Comments

  • Photo: John

    John commented on :

    I think you are asking about using the approximation of all the stars being points on the inside of a big sphere with us at the centre? Like when you go into a planetarium and they project all the stars onto a big dome above you.

    This generally seems like a pretty reasonable way of looking at the universe, as most things appear very small and almost stationary as they are so far away.

    Where it might start to become a problem is where some things are relatively close, like the moon. For example if you were to travel a long way on the earths surface the moon would appear to move relative to the other stars (even if it was stationary) because the place you’re viewing it from has changed. (called “parallax effect”)

    Another problem might be if you were looking at the movement of objects. Imagining them on a 2D sphere it might look like they were about to collide, whereas in reality (3D!) they might be very far apart because their distances from earth are different.

    So overall I would say it is a useful approximation, but (as with all approximations) you need to be aware of its limitations.