• Question: could it be possible for a star i see to have been destroyed a few years ago depending on how far it is?

    Asked by josh to Colin, John, Kevin, Shikha, Triona on 18 Nov 2014.
    • Photo: Kevin Motherway

      Kevin Motherway answered on 18 Nov 2014:

      Great question Josh

      the sun is 8 light minutes away so if it exploded we wouldn’t know for 8 minutes until the light reached us. Betelgeuse in Orion is a red giant which is overdue to go supernova but it’s 640 light years away meaning it could have exploded 649 years ago but the light of the explosion hasn’t reached us yet!

      So you’re always looking into the last when you’re looking at the stars! Even 8 minutes into the past for our own sun

    • Photo: Shikha Sharma

      Shikha Sharma answered on 21 Nov 2014:

      Hi Josh 🙂

      Very good question!!!! Let me tell you one interesting thing!!!! When we look at sky whatever we see, its all in past!!!!! How??? Light from any object from universe takes some time to reach us. When it reaches we get to see the object exactly the same when the light left the object in past. Now let me elaborate a bit. A light ray just started from Sun, reaches on Earth after approx. 8 mins. Therefore when it reaches to us we see the Sun exactly as it was 8 mins ago. In a way we see Sun always 8 mins past!!!!!!. Now let’s assume, a distant star emits it’s last light rays just before getting destroyed into a black hole. The star is one light year away from earth, therefore those last lights will take 1 year to reach us. When it reaches us we shall see the star alive. However in reality the star have already destroyed!!!!
      Believe me, this is a very very interesting realization by physicists and astronomers. They try to focus their telescope at very high distance from earth to get an idea how the universe was in past. More you look at distance more you go back to past of universe. Now can you just imagine how we came to know the origin of universe 13 billion years back!!!!!!