I find this funny and sad at the same time: someone at NASA had to write an article explaining the obvious to those claiming that the world will end in 2012 because of a nearby supernova.
Here's how Francis Reddy, from NASA's Goddard Space Flight Center, starts his article:
Given the incredible amounts of energy in a supernova explosion — as much as the sun creates during its entire lifetime — another erroneous doomsday theory is that such an explosion could happen in 2012 and harm life on Earth. However, given the vastness of space and the long times between supernovae, astronomers can say with certainty that there is no threatening star close enough to hurt Earth.
But the fact is that there are no stars near Earth that can go supernova and disrupt our planet, as Reddy explains right after that paragraph:
[F]or Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away. All of the nearby stars capable of going supernova are much farther than this.
Reddy then spends quite a few paragraphs explaining supernovae, why they happen and how they affect nearby objects. [NASA]