Can finish the world by the explosion of a supernova?

Ever wondered where you should have gold or silver of your rings or earrings? What about your mercury thermometers? I give you a hint: it has an extraterrestrial origin. But I do not mean little green men brought to him a planet rich in gold, silver or mercury, but formed outside our planet. Specifically, in supernova explosions.

What would happen if a supernova explodes near us? First, define "close" to the outbreak affects us, should be at a minimum distance of about 30 light years for a supernova star 10 times the mass of the Sun.

In that explosion is generated all kinds of electromagnetic waves, including X-ray feared that would traverse the ozone layer in the same way that a bullet through tissue paper and our DNA would be affected creating mutations. Far from becoming Spider-Men or Wolverine, our bodies would dying cancer victims.

To survive, the nights would really frost, several tens of degrees below zero, with all that that entails for the survival of the species. We would not last long. That's assuming we had some air to breathe, which seems unlikely.

Now comes the note of calm: all nearby stars that explode as supernovae are far enough as to not affect us. The candidate who you think could explode with more ahead is Betelgeuse, in the constellation of Orion, located about 640 light years. You may have already exploded. If so, from the time of the explosion, it will take 640 years to know, which is the time it takes light to reach us.