Question: hi Helen I'm Niamh and I'm 12 and i find Science quite difficult but this has really helped me answer my questions. What is a black and what does it do?

Helen Johnson answered on 21 Nov 2014:

Hi Niamh! That’s brilliant, good to hear 🙂 I’ve really enjoyed taking part – don’t want it all to end!
Do you mean a black hole? A black hole, in the most common case, is formed when a really massive star comes to the end of its life – it runs out of the Hydrogen it’s turning into Helium. Some time after this the star will explode in what we call a ‘supernova’, and become very, very bright. What’s left of the star will then collapse back in on itself, becoming incredibly tightly packed (high density). The density is so high that the star has a very strong gravitational field – so strong that even light can’t escape it! We call them black because we can’t see the centre of them. Hope this helps.