• Question: how small can a black hole be

    Asked by anon-190901 to Kathryn, Graeme, Chris, Anne, Agnes, Adam on 13 Nov 2018.
    • Photo: Graeme Poole

      Graeme Poole answered on 13 Nov 2018:

      Black holes can be very small in size. They have a huge amount of mass but this is crushed down to a very tiny space. The smallest ones that we have seen are only about 20km across, but still contain more more mass than the entire Sun!!

    • Photo: Anne Green

      Anne Green answered on 13 Nov 2018:

      The smallest black holes that we’ve found weigh a few times more than the Sun, but squashed into a really small space about 15 miles across (the Sun is nearly a million miles across).

      It’s possible that really tiny black holes can form just after the Big Bang. They could be as light as a fraction of a gram and a tiny fraction of a centimetre across. Black Holes formed just after the Big Bang are called Primordial Black Holes. They’re one of the things that Stephen Hawking worked on.

    • Photo: Kathryn

      Kathryn answered on 13 Nov 2018:

      The smallest is about 18 km that has been found I think.

    • Photo: Adam McGuinness

      Adam McGuinness answered on 13 Nov 2018:

      I don’t know, I’m sorry!

    • Photo: Agnes Wojtusiak

      Agnes Wojtusiak answered on 13 Nov 2018:

      That black hole might not take up much space, but it would still have the mass a few times bigger than our Sun’s!!

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