It is believed that many of the meteorites found on Earth are the remnants of one titanic collision that took place in the solar system over 460 million years ago. However, after researchers focused their efforts on the meteorites that fell to Earth prior to this impact, they found that the composition of these early space rocks was strikingly different from today's samples.
“We found that the stream of meteorites hitting Earth in the past is very different from what we see today,” said lead author of the study, Philip Heck. “Looking at the meteorites that have fallen to Earth over the past hundred million years, we do not see the full picture. It is like looking at one snowy winter day and concluding that every day is snowy, even though there is no snow at all in summer. '
By studying the various meteorites that have hit Earth, scientists can develop a better understanding of how the basic building blocks of the solar system formed and evolved.
“We knew almost nothing about the flow of meteorites to Earth in ancient times until we did this study,” said co-author Birger Schmitz of Lund University in Sweden. 'But the traditional point of view is that the solar system has been very stable over the past 500 million years. But why, then, the stream of meteorites 467 million years ago is so different from today's observations. '
To find out exactly what the stream of meteorites was before the big impact, Heck and his colleagues had to study meteorites that fell more than 466 million years ago. Such finds are rare, but the team was able to find them on micrometeorites – tiny particles of space rocks less than 2 mm in diameter that have fallen to Earth in the past. With the help of colleagues from Russia, samples of rocks from the ancient seabed, hidden today in the valley of one of the rivers on the territory of the Russian Federation, were studied. After dissolving the stones in acid, scientists were able to identify microscopic chromite crystals in them.
“Chromium spinels – crystals that contain mineral chromites, remain unchanged even after hundreds of millions of years,” Heck explained. 'Given this immutability, we were able to determine what exactly created the micrometeorites.'
According to the scientist, knowledge about the various types of meteorites that fell to Earth in the past makes it possible to better understand how the asteroid belt was formed and what collisions were present in the solar system.
Sources: phys
