The object that hit Jupiter last weekend released thousands of times more energy than the massive Tunguska blast in Siberia in 1908, say astronomers.
For planetary scientists who chronicled a comet's collision with Jupiter 15 years ago, the latest impact is an unexpected gift.
"It's an exciting time," says University of California at Berkeley astronomer Michael Wong. Dr. Wong and his colleagues pulled an all-nighter to capture and process images of the scar using the Hubble Space Telescope.
Initial estimates put the size of Jupiter's assailant at a few hundred yards across. When it hit Jupiter's upper atmosphere and exploded, it released thousands of times more energy than the oft-cited Tunguska explosion in Siberia in 1908, says Keith Noll, an astronomer at the Hubble Space Telescope Institute in Baltimore.
Recent estimates place the punch from the cosmic object that exploded over Tunguska at between 3 million and 5 million tons of TNT. That puts Jupiter's impactor into the continent-buster class.
It's not clear yet where the impactor came from. One likely source is the pool of short-period comets – icy objects that once resided beyond Neptune, but got pulled in toward the gas giants, notes Michael A'Hearn, a researcher at the University of Maryland.
Another possible source, he says, is a group of asteroids known as Trojans. These lie in two broad groups along Jupiter's orbit – one ahead of the planet, the other behind it.