James Owen
for National Geographic News, September 15, 2005
Scientists turned planetary detectives say they may have solved a solar system whodunit: What caused a cataclysmic asteroid assault on Earth and neighboring planets some 3.9 billion years ago?
Researchers suspect that the devastating bombardment, which lasted between 20 and 200 million years, originated in the main asteroid belt between Jupiter and Mars.
The U.S.-led team based their conclusion on evidence found in the unhealed wounds of ancient asteroid collisions left on the moon and the inner planets Mars, Mercury, and Venus.
Writing in tomorrow's issue of the journal Science, the scientists note that the intense period of crater-making impacts, known as the late heavy bombardment, was likely caused by repositioning of the solar system's giant outer planets.
http://news.nationalgeographic.com/news/2005/09/0915_050915_asteroids.html
Forum 
