• Question: How many stars do you think there are?

    Asked by liverpoolfcman to Cathal, Ciara, Emma, Michael, Sive on 14 Nov 2013.
    • Photo: Michael Nolan

      Michael Nolan answered on 14 Nov 2013:

      Always a good question:

      1. If the Universe is infinte in extent then the number of stars may be infinite. That is a hard idea to get your head around.

      2. If the Universe is finite in size, then the number of stars is some number. Estimating say 300 billion (300000000000) in the Milky Way (our galaxy) and up to 100 trillion (100000000000000) and there are around 170 billion galaxies (170000000000), then if you do some numbers for average number of stars in a galaxy, you get
      100000000000000000000000 stars (24 zeros there!),
      assuming the universe is 13.8 billion light years across

      3. Some researchers think the Universe is 47 billion years across, so lets add another zero to that number, givng
      1000000000000000000000000 stars

      So, either way, the number of stars in the Universe is a very large number indeed, as befits are Universe nearly 14 billion years young.

      M

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