NASA says a space telescope observed a flare-up of dust surrounding a distant young star that might be the consequence of a collision between two large asteroids, a kind of collision that can contribute to the creation of planets or moons.

Astronomers had been using the Spitzer Space Telescope to track a star known as NGC 2547-IDB when it suddenly displayed a huge increase in surrounding dust from August 2012 to January 2013.

"We think two big asteroids crashed into each other, creating a huge cloud of grains the size of very fine sand, which are now smashing themselves into smithereens and slowly leaking away from the star," says graduate student Huan Meng of the University of Arizona, Tucson, lead author of a paper on the study appearing in the journal Science.

The thick cloud of dust is orbiting the zone around the star where rocky planets will normally form, the researchers say.

The observations of NGC 2547-IDB are providing first-of-its-kind data on the processes and outcomes of collisions that can lead to creation of planets like Earth, they say.

"We are watching rocky planet formation happen right in front of us," says George Rieke, a University of Arizona study co-author. "This is a unique chance to study this process in near real-time."

The collision at the star about 1,200 light-years away in the constellation Vela may be likened to the one thought to have happened early in our solar system's history between the proto-Earth and a Mars-size object that led to the creation of our moon, the researchers say.

The collision suggests the star, thought to be around 35 million years old, may be surrounded by a reservoir of planetary embryos or large asteroids, they say.

While Spitzer has observed the dusty aftermaths of suspected asteroid collisions before, this is the first time astronomers have been able to collect data over an extended period from both before and after a possible planetary system smashup.

"We not only witnessed what appears to be the wreckage of a huge smashup, but have been able to track how it is changing -- the signal is fading as the cloud destroys itself by grinding its grains down so they escape from the star," says UA study co-author Kate Su.

It would take 10 to 15 impacts of asteroids or planetary embryos to create enough debris to form a rocky Earth-sized world, the researchers estimate.

That's just what Spitzer has spotted, they say.

"This is the first detection of a planetary impact outside our solar system," Meng says.