• Question: What would happen if the Milky Way ever came in contact with Andromeda?

    Asked by 572enek49 to Emma, Karla, Shane, Stephen, Yang on 10 Nov 2017.
    • Photo: Shane Mcdonagh

      Shane Mcdonagh answered on 10 Nov 2017:


      Well scientists predict that this is going to happen, but not to worry, it’s not due to happen for another 4 billion years or so.
      As both galaxies contain a lot of mass gravity will cause them to kind of bump off each other and eventually merge, forming one now much bigger galaxy.

      Below is a video that contains simulations of what that will look like:

    • Photo: Stephen Rhatigan

      Stephen Rhatigan answered on 11 Nov 2017:


      Nice question. Estimates are that the Andromeda Galaxy is moving towards our galaxy at around 400,000 km/hr but as Shane said, it will take billions of years to close the distance.
      To understand why collisions between stars will be unlikely when the galaxies merge, think about it like this:
      If our Sun was the size of a football sitting in the Phoenix Park in Dublin, the nearest star, which is Proxima Centauri, would be the size of a golf ball sitting in Miami, Florida.
      Now think about this:
      At the center of the Milky Way and Andromeda galaxies are supermassive black holes which have billions of times the mass of our sun.
      As the galaxies merge together, so too will the black holes. They will begin by orbiting about each other, getting closer and moving faster. The energies involved are so huge that stars will be “slingshotted” out of orbit.
      When the black holes are about 1 light year apart (9.5 trillion kilometers) they will begin to produce gravitational waves which contract and expand space itself.
      The 2017 Nobel Prize in Physics was awarded for the first detection of gravitational waves. This happened in September 2015 – 100 years after Einstein predicted their existence in his theory of General Relativity.
      The gravitational waves which were detected came from the collision of two black holes and took 1.3 billion years to arrive at Earth.

    • Photo: Emma Hanley

      Emma Hanley answered on 13 Nov 2017:


      I think Shane and Stephen answered this so good, I have nothing else to add.

    • Photo: Karla Dussan

      Karla Dussan answered on 13 Nov 2017:


      Thanks to @Shane and @Stephen for such great explanations!

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