• Question: how large is the universe amd at what rate is it moving away from each other and how many supernovas do you think there are in one year??

    Asked by 08cguscott to Evan on 20 Jun 2011.
    • Photo: Evan Keane

      Evan Keane answered on 20 Jun 2011:

      You might want to read this other answer where I talked about the size of the Universe http://ias.im/44.669

      Regarding the rate at which it is expanding – this can be measured by examining the “red-shift” of galaxies (simply how fast they are moving away from us). The rate of expansion is called the “Hubble constant” and galaxies 1 mega-parsec (about 3 million light years) away are moving away at about 75 kilometres per second.

      I don’t have to guess how many supernova happen per year, because when they go off they leave a lot of evidence lying around after them so we can work it out. In our Galaxy there is about 1 supernovas every 50 years. But you don’t have to keep looking for 50 years to see one – just look at loads of galaxies and you can see supernovae every day! A famous one happened in the “Whirlpool Galaxy” about a month ago.

Comments