[rob74]

Another quote from later in the article:

> a very close supernova could inflict massive harm to life on Earth

...but they fail to mention how close this "very close" is. I assume 700 light years (Betelgeuse) is a little bit far away to qualify? As a total amateur in astronomy/astrophysics, I would assume that if there were any "very close" stars that are massive enough to go supernova, they would already be known?!

[speakeron]

50 light years is the generally accepted distance that would cause problems. There are no candidates this close that could cause a type II supernova (this is when a massive old star, like Betelgeuse, collapses), but there could be potential type I supernovae lurking closer. These are binary pairs of a white dwarf and another star where the white dwarf is accreting mass from the companion and reaches a limit (the Chandrasekhar mass) where runaway nuclear fusion spontaneously occurs.