Huge “star-quake” rocks Milky Way

From the BBC, via Brad DeLong:

Astronomers say they have been stunned by the amount of energy released in a star explosion on the far side of our galaxy, 50,000 light-years away.

The flash of radiation on 27 December was so powerful that it bounced off the Moon and lit up the Earth's atmosphere.

… If the explosion had been within just 10 light-years, Earth could have suffered a mass extinction, it is said.

“We figure that it’s probably the biggest explosion observed by humans within our galaxy since Johannes Kepler saw his supernova in 1604,” Dr Rob Fender, of Southampton University, UK, told the BBC News website.

One calculation has the giant flare on SGR 1806-20 unleashing about 10,000 trillion trillion trillion watts.

“This is a once-in-a-lifetime event. We have observed an object only 20km across, on the other side of our galaxy, releasing more energy in a 10th of a second than the Sun emits in 100,000 years,” said Dr. Fender.