A catastrophic collision between two asteroids deep in the solar system led directly to the death of the dinosaurs, scientists reveal this week.
The cosmic crash, 160 million years ago, caused one space mountain, more than 100 miles wide, to break into an “asteroid shower” of numerous giant rocks that spiralled in to threaten the inner planets.
After nearly 100 million years circling the sun, one struck Mexico’s Yucatan Peninsula, 65 million years ago, creating the Chicxulub crater triggering a mass extinction that did for the dinosaurs.
Other fragments became missiles that blasted out a prominent young crater on the Moon called Tycho, plus similar craters that have been detected on Mars and Venus. A fifth of the “Near Earth Objects” – asteroids that still threaten to hit Earth today – are from the same asteroid shower.
One large remnant of the original shattered space rock that is still roaming the solar system has been identified as an asteroid called Baptistina, scientists report in the science journal Nature.
The Nasa-funded celestial detective work was carried out by a joint team of scientists from the Southwest Research Institute in Colorado and Charles University in Prague.
They traced the devastating impact in Mexico back to a breakup event in the main asteroid belt, between Mars and Jupiter, around 160 million years ago, plus or minus 20 million years.
Baptistina’s parent world was shattered into fragments including around 300 that were more than ten km wide (around 6 miles) and 140,000 bigger than one km. It doubled the number of impacts happening on Earth, the Moon, Mars and Venus over the last 100-200 million years, say the team.
Dr William Bottke, of Colorado, and his team combined astronomical observations with computer simulations to calculate how the orbits of the asteroid fragments evolved over time under pressures such as sunlight.
They calculated a 90 per cent probability that the 110-mile wide Chicxulub crater in Mexico was formed by one of the giant missiles, and the threat of more impacts is not over. Asteroids are regularly being spotted passing close to Earth.
Dr Bottke said: “We are in the tail end of this shower now. Our simulations suggest that about 20 percent of the present-day, near-Earth asteroid population can be traced back to the Baptistina family.”
©PAUL SUTHERLAND, Skymania.com
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