Asteroid Belt Holds Clues To Era of Swinging Planets

"The asteroid belt, a ring of rubble between Mars and Jupiter, has sometimes been written off as discarded leftovers from the solar system's start. But new research published in the journal Nature shows that the belt actually formed during an unruly later era, when planets themselves were on the move."

"For decades, astronomers have thought the belt formed from the same cloud of dust and rock that made our planets. That theory was based on observations of just a few asteroids in the 1980s. Astronomers have seen a lot more asteroids since then."

"'There have been some really large surveys over the past decade or so that have expanded our understanding from a couple thousand asteroids to hundreds of thousands of asteroids,' says Francesca DeMeo, an astronomer at the Harvard Smithsonian Center for Astrophysics.The asteroid belt, a ring of rubble between Mars and Jupiter, has sometimes been written off as discarded leftovers from the solar system's start. But new research published in the journal Nature shows that the belt actually formed during an unruly later era, when planets themselves were on the move."