The sun might have captured thousands or even millions of asteroids from another planetary system during an encounter more than 4 billion years ago, according to a report today in the journal Nature.
Such an interstellar ballet would explain many mysteries of the outer solar system, including the strange behavior of the recently discovered Sedna, the system's most distant known object, which occupies a strange elongated orbit far beyond Pluto.
If the alien asteroids could be found and studied, these bodies could provide testimony to the conditions under which the sun and the solar system formed, a time otherwise lost.
Astronomers say the sun was born 4.5 billion years ago as part of a dense cluster of more than 1,000 stars that has long since disappeared.
The star that nearly collided with our solar system so long ago could be on the other side of the galaxy by now.