Astronomers have found a comet-like object they believe was created by the collision of two asteroids, and may be linked to the rogue rock blamed for wiping out the dinosaurs.
The object, known as P/2010 A2, was circling about 144 million kilometres from Earth in the main asteroid belt between Mars and Jupiter when it was spotted last week by the Hubble Space Telescope.
"The truth is we're still struggling to understand what this means," says lead scientist Dr David Jewitt with the University of California at Los Angeles. "It's most likely the result of a recent collision between two asteroids."
"It'd be the first case we've seen of an asteroid smash happening, basically caught in the act."
The object resembles a comet, but its nucleus is severed from its tail, which "has a very strange appearance, the likes of which we've never seen before," says Jewitt.
Studies of the object - and searches for similar ones - would improve scientists' understanding of how asteroids break apart, information that may be useful to thwart a future asteroid strike on Earth.
"The thing that we want to understand is how the asteroids smash into each other and destroy each other," says Jewett. "It might help us understand even how to destroy an asteroid and prevent one from hitting us."
Scientists believe a giant comet or asteroid that hit Earth about 65 million years ago was linked to the extinction of the dinosaurs, possibly by throwing up dust or chemical clouds that blocked the sun or by igniting global wildfires.
Calculations show the orbit of P/2010 A2 is related to the group of asteroids, known as the Flora family, which produced that asteroid.
NASA is working to catalogue at least 90% of the estimated 1000 objects that approach Earth and are larger across than one kilometre, about two-thirds of a mile. The agency's proposed budget for the year beginning 1 October includes a US$16 million (A$17.8 million) annual increase to step up that effort.