Hopefully we all know what a Supernova is from our Physics GCSE (but if not – click the link to see what Wikipedia has to say.)
A star in the Orion constellation called Betelgeuse (pronounced Beetle Juice) is coming to the end of its considerably long life. Measurements astronomers can take from Earth show that it is losing mass rapidly, a sign of imminent supernova explosion.
If this happens (and they reckon it might be in the next few years) an explosion so powerful it lights up our sky like another sun will occur, lasting weeks.
In fact – the explosion has probably already occured – being 643 light years away the light that reaches us and is picked up by our telescopes is already 643 years old – we are looking at the past!
These explosions are very important – the heavy atoms are made in them (parts of you are literally star dust).
This has happened in the past – with the Chinese recording such an even in 185 AD (over 2000 years ago)