SAVANTS USED MOON CRATERS TO IDENTIFY EARTH ASTEROID SHOWER 800-M YEARS AGO

An asteroid measuring over 100 kilometers in diameter caused disruption that led to a shower of meteorites hitting Earth and the moon some 800 million years ago, according to findings announced by a group of researchers from Osaka University and the University of Tokyo and reported by Koki Matsumoto of the Mainichi Shimbun on July 23, 2020.

It is estimated that meteorites, with a combined mass of at least 40 quadrillion to 50 quadrillion kilos hit Earth, making them between 30 times and 60 times heavier than the asteroid believed to have wiped out the dinosaurs some 65 million years ago. Researchers announced their findings in the electronic edition of British science journal Nature Communications on July 22. There have been papers published on the theory that phosphate concentration in the ocean surged to four times its original amount around 800 million years ago, stimulating the diversification of species. The team suggests it is possible that the asteroid shower brought phosphate to Earth, and led to a change in the environment.

Although it is thought that astronomical objects measuring over 10 kilometers in diameter hit Earth around once every 100 million years, the craters they leave are hard to find due to weathering and other factors and evidence of the events can reportedly only be traced back as far as some 600 million years ago.

The research group investigated the asteroid shower that hit Earth based on craters on the moon, which have barely weathered, by analyzing photographs taken by lunar orbiter spacecraft Kaguya of 59 craters spanning 20 kilometers or more in diameter. In doing so they found that between eight and 17 craters, including one called "Copernicus," and other traces were formed around the same time. Using samples brought back by the US Apollo program and other missions, the group estimated the lunar craters' formation dated back some 800 million years. It is known that Earth has been hit by meteorites about 20 times the mass of those that hit the moon.

According to the group's calculations, an asteroid shower with a mass of at least 40 quadrillion to 50 quadrillion kilograms hit Earth, which would make it the largest to have occurred in the past 2.5 billion years.