for National Geographic News
Small meteorites impact our planet several times a year, anddespite Hollywood's doomsday scenarioslife on Earth survives. Almost all of these meteorites are from asteroid collisions that occurred 3 to 60 million years ago.
A new study suggests, however, that the violent destruction of an asteroid can create a long-lasting rain of meteorites. The space rocks would be delivered to Earth by a "meteorite express," the study says.
Total travel time to our planet: a mere hundred thousand years.
The research, which is described in tomorrow's edition of the science journal Nature, was conducted by scientists who studied meteorites preserved in 480-million-year-old sediments in southern Sweden.
The scientists found that the meteorites contained gases produced by cosmic rays that suggest the meteorites' transfer to Earth occurred much faster than for more recent ones.
The data led researchers to conclude that a violent collision in our solar system's distant asteroid belt 500 million years ago produced meteorites that traveled to Earth in a relatively scant hundred thousand years.
"It's the first physical confirmation of unusually short transfer times [of meteorites] after a major asteroid collision," said Philipp Reza Heck, the report's lead author. Heck studies cosmochemistry at the Swiss Federal Institute of Technology in Zurich.
His research was partially funded by a grant from the National Geographic Society's Committee for Research and Exploration.
Diverted by Jupiter
The general term "meteor" comes from the Greek meteoron, meaning "phenomenon in the sky." Meteoroids, in particular, are fragments of asteroids produced by collisions.
Meteoroids in our solar system spend most of their time in the asteroid belt between Mars and Jupiter, unless they encounter a phenomenon known as orbital resonance and change course.
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