[ad_1]
By Till Mundzeck, dpa
Toronto – The fire by a terrestrial asteroid has been doubled to triple by nearly 300 million years ago. Researchers of an age badysis craters of impact on the moon conclude that. Scientists around Sara Mazrouei of the University of Toronto (Canada) work in the American newspaper "science"The reason for this increase is therefore not clear.
Researchers have long studied the frequency of asteroid impact during the Earth's history. This is not so easy because plate tectonics and erosion can make craters disappear over geological time. The team therefore badyzed a celestial body having the same probability of impact as Earth, but no plate tectonics and little erosion – the moon. "The only obstacle was finding a precise way to date the big craters on the moon," said co-author William Bottke of the Southwest Research Institute in Boulder, Colorado.
"Young" crater of impact on the moon.
– Ernie Wright, NASA Goddard / dpa
Measurement with lunar probe "Lunar Reconnaissance Orbiter"
The scientists were successful: with the lunar probe "Lunar Reconnaissance Orbiter" (LRO) from the US NASA space agency, they measured the thermal radiation from the craters of our satellite's impact during the moonlit night . Big rocks are hotter than finely ground materials. This in turn helps to draw conclusions about the age of the craters, because the younger impact craters are bigger because they succeed one another over the course of millions of years under the influence of the craters. effect of a constant hail of micro-meteorites from outer space.
The researchers have dated all the major lunar craters that have appeared over the past billions of years. The temporal distribution has created a surprise: 290 million years ago, the asteroid impact rate was suddenly multiplied by two or three. The same applies to the Earth, which also has fewer old craters than the younger ones. "This study reveals that the Earth has fewer old craters on solid ground due to erosion, but because the frequency of impacts is lower 290 million years ago," Bottke explained. .
Graphic illustrating the increase of the impact rate on the Moon and the Earth.
– Dr. R. Ghent, University of Toro
No explanation yet for the increase
Why the frequency of asteroid impacts has suddenly increased at that time, the researchers can not yet explain. It is possible that large collisions in the asteroid belt between Mars and Jupiter have sent more asteroids crashing on the ground, they speculate. "We can now use this technique to examine the surfaces of other planets to see if they also have more impact," Bottke said.
The discoveries also have implications for the history of life on Earth, shattered by mbadive extinction events and the rapid evolution of new species: "Although the driving forces behind these events are complex, the asteroidal impacts have certainly a role to play in this ongoing saga played ".
Source link
