• Question: do stars move around or are they continously in the same spot?

    Asked by Benmacanbeatha to Colin, John, Kevin, Shikha, Triona on 15 Nov 2014.
    • Photo: Kevin Motherway

      Kevin Motherway answered on 15 Nov 2014:

      The stars appears fixed in our sky and from our perspective they do not change but over 100’s of thousands of year the constellations so familiar to us do change as stars move around the Milky Way. All the stars that you can see with the naked eye are all located in a tiny part of the spiral arm of the Milky Way in which the Earth is located. You can see more distant stars and galaxies with a pair of binoculars, but using really high resolution telescopes the minuscule movement of stars can be tracked, but the average will never really notice the movement over a lifetime of observing.

    • Photo: Shikha Sharma

      Shikha Sharma answered on 16 Nov 2014:

      Hi Benmacanbeatha ,
      Stars do move. Most of the galaxies are spiral galaxy like our galaxy. All matters in a galaxy move around the center of the galaxy. This movement actually create balance against the gravitation force between matters. Therefore they do not fall on each other due to pull of gravitation. Hence stars also move around the center of the galaxy. However, we don’t see or realize it as we are also moving around the center of the galaxy along with Sun. So the relative velocity between earth and star is very small. Though, stars and other matter are moving at great speed around center of galaxy. Sun is 24000 light years away from the centre of the galaxy. It takes about 230 million years to make one round around the centre of the Galaxy at speed of 220 Km/s.