• Question: What is a black hole and is it dangerous?

    Asked by Sazzmeister to Adrian, Gaia, Jim, Scott, Vicky on 11 Mar 2016.
    • Photo: Adrian Buzatu

      Adrian Buzatu answered on 11 Mar 2016:

      A black hole is produced when a very large mass is present in a small volume of space. That is typically the case when large stars explode at the end of their lifetime in supernova explosions. These black holes have therefore about the same mass as a star.

      They are dangerous as once you get too close to them and pass a line of no return called horizon, then you can never come back. But they are not that dangerous in fact. If the star has planets, these would continue to orbit around the star at almost the same distance as before. Therefore they would not fall into the black hole created by the star.

      There are also huge black holes at the centre of galaxies. Again they are not dangerous, as the matter in the galaxy orbits around the centre of the galaxy instead of falling into it.

    • Photo: Scott Lawrie

      Scott Lawrie answered on 11 Mar 2016:

      A black hole happens when a star is so huge and old that it has used up all its fuel and cannot push against gravity anymore. Gravity then can finally squeeze the star up into a tiny ball with nothing to ever stop it getting smaller! You then have a bit of space with several stars’-worth of mass squeezed into something the size of a city! The gravity of this tiny thing is enormous – it sucks everything in and they cannot ever escape. Even light – the fastest thing there is – cannot move fast enough to escape! That’s why they’re called Black Holes 👿

      Black holes are horrible places. You really wouldn’t want to go anywhere near one. But luckily there are none anywhere near us, so you really don’t have to worry. In fact, even if the Sun were to magically be replaced by a black hole (this will never happen!!) we still wouldn’t be sucked into it… we’d just get very cold 🙁

    • Photo: Gaia Andreoletti

      Gaia Andreoletti answered on 11 Mar 2016:

      Imagine matter packed so densely that nothing can escape. Not a moon, not a planet and not even light. That’s what black holes are — a spot where gravity’s pull is huge, ending up being dangerous for anything that accidentally strays by.

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