How loud is a supernova?

Answer 1

Very. Hundreds to millions of times the solar output, squeezed into a few seconds. A supernova at one of our closest neighbors would end all life on Earth.... not maybe from the blast, but at least from retaining heat from our own Sun.

Answer 2

"In space, no one can hear you scream" - from Alien.

As the sound has nothing to pass through, you wouldn't hear anything.

See related question for a comparison on hydrogen bombs.

Answer 3

Yes. The one thing in the universe more powerful than a supernova is a quasar. A quasar is an extremely bright energy source found in the cores of some galaxies. They are probably disks of material falling into supermassive black holes several hundred million to several billion times the mass of the sun. This material is moving at velocities approaching the speed of light and is so hot that the nuclei of atoms fall apart. What doesn't disappear within the black hole is ejected in twin jets of subatomic particles moving at nearly the speed of light.

Answer 4

A supernova can reach sound levels of around 110 to 120 decibels from a distance of about 50 light years away, which is roughly equivalent to the noise of a chainsaw. However, since sound cannot travel through the vacuum of space, we would not actually be able to hear a supernova from Earth.