• Question: Is it possible to have an another galaxy the same as ours?

    Asked by Djenne to Heather, Helen, Hugh, Jane, Julian on 7 Nov 2014.
    • Photo: Julian Onions

      Julian Onions answered on 7 Nov 2014:

      Yes – there are several very similar galaxies to our own we have seen.

      A galaxy called NGC 6744 has been seen which astronomers think is most similar to our own milky way,
      http://en.wikipedia.org/wiki/NGC_6744
      but there are lots of galaxies that look very similar to what we think our own galaxy looks like.

    • Photo: Jane MacArthur

      Jane MacArthur answered on 7 Nov 2014:

      Our Milky Way is a spiral galaxy, and these are classified by the size of their bulge and appearance of the spiral arms. There are many spiral galaxies which are similar to our own, though clearly this is limited by what we can currently see and detect with telescopes, and as they are so far away, our classifications are still somewhat crude.

      Intuitively, I would think the chances of a galaxy being completely identical to ours are very low, however, this amazing image was taken with the Hubble Space Telescope:
      http://hubblesite.org/gallery/album/the_universe/pr2004007a/large_web/
      The width of that image is 1/10th of the diameter of the Moon, and nearly 10,000 galaxies can be seen in it, so with the vastness of space and number of galaxies out there, anything is possible.

    • Photo: Heather Campbell

      Heather Campbell answered on 9 Nov 2014:

      Yes very possible! But at the moment we don’t know exactly what our galaxy looks like, because we are inside the galaxy it is incredibly hard to see exactly what it looks like. This is the same problem as when you are in the middle of a city you can’t tell what it looks like, you need to fly a helicopter over and take a photo of the city to see what it looks like. With our own galaxy we can’t travel far enough away (only to the edges of our own solar system) to be able to take an image looking back. Instead we need to take very accurate measurements of the distances to the stars and measure their motions (all the stars are orbiting around within our galaxy) to enable us to build up a 3D map of what the galaxy looks like. This is what the Gaia Satellite mission is doing right now (see gaia.ac.uk for more details). Once we know what our galaxy looks like, then we can begin to answer “if there are other galaxies the same as ours?” We know some things already, that the galaxy has a disk, a central bulge and some spiral arms (but we’re not sure how many). When we observe other galaxies we see these features clearly in many of the young galaxies, which we call “star-forming”, as they are making stars today.

    • Photo: Helen Johnson

      Helen Johnson answered on 9 Nov 2014:

      It depends what you mean by the same 🙂 Do you think there’s another galaxy out there with life in it somewhere?
      There are lots of different types of galaxies, but ours (the Milky Way) is what we call a spiral. These have lots of stars being formed in bright, blue spiral arms, and a ‘bulge’ of older, redder stars towards the middle. We’ve seen lots like this, especially in the nearby Universe. If we look further away (further back in time!) star forming galaxies start to look a lot ‘messier’ than these pretty spirals – these are the galaxies I’m most interested in.

Comments

  • Photo: Djenne

    Djenne commented on :

    I meant ‘the same’ as in a identical almost parallel universe. If there are so many different types could there be similarities? meaning there could be a planet like earth or a solar system like ours?