The brightest space explosion in history
It may not look like much more than an orange splotch, but the picture to the right shows one of the largest cosmic explosions ever recorded. NASA last week first picked up on the bright blasts of radiation, which are thought to be coming from the center of a galaxy about 3.8 billion light years from Earth. Here, an instant guide to the incredible explosion:
A burst of gamma rays like this typically accompanies the destruction of a distant star. "But that's usually a one-time event," says Irene Klotz at Discovery, a powerful blast of radiation followed by nothingness. "So far, the source has brightened four times since Tuesday" and remains bright.
What do scientists think might be happening?
Astronomers suspect what we are seeing is an unfortunate star that drifted too close to a supermassive black hole at the center of its galaxy and was ripped apart by fierce gravity. The ionized gases released by the star's destruction formed a swirling "disk of plasma" around the black hole, which blasted unimaginable beams of energy out into space. It's these that we are continuing to see.
Don't black holes swallow stars all the time? Why is this different?
The "disk" that formed around the black hole was facing our galaxy, so the beams of energy were essentially aimed directly at us. "The best explanation at the moment is that we happen to be looking down the barrel of this jet," said Andrew Levan at the University of Warwick. Normally, what we see is simply the final blast of rays from the star's destruction. This time, we're seeing the star's death throes in all their glory.
Could the explosion harm us?
No — it's too far away to even be detectable by all but the most powerful telescopes, says Phil Plait at Discover. And thank goodness for that. The beams of energy, for a time, "shone with the light of a trillion suns." Had we been in that galaxy at the time and in the path of those beams, "well, the Earth would have been in a bad way."