Giant Asteroid Impacts Shaped Our Ancient Earth by Vaporizing Oceans

Billions of years ago, our ancient Earth was still forming as molten material mixed and churned. Now, scientists have found that giant asteroid impacts may have played a huge role in this geological evolution. The findings reveal a little bit more about how our planet first formed.

"When we look at the present day, we have a very high fidelity timeline over the last about 500 million years of what's happened on Earth, and we have a pretty good understanding that plate tectonics and volcanisms and all these kinds of processes have happened more or less the same way over the last couple of billion years," said Lindy Elkins-Tanton, one of the researchers, in a news release.

Yet during the Earth's first 500 million years, there was a period called the Hadean; this period is far less researched, and scientist assumed it was wildly hot and volcanic. Now, scientists have found that asteroid bombardment probably had a profound effect on the geological evolution of Earth.

Prior to four billion years ago, Earth was resurfaced over and over by impact-generated melt. In addition, large collisions may have repeatedly boiled away oceans into steamy atmospheres. It's like that during Hadean Earth, the asteroidal collisions severely altered the geology of our planet. Researchers estimate that Hadean Earth could have been hit by one to four impactors that were more than 600 miles wide and capable of global sterilization, and by three to seven impactors more than 300 miles wide and capable of global ocean vaporization.

"Prior to approximately four billion years ago, no large region of Earth's surface could have survived untouched by impacts and their effects," said Simone Marchi, one of the researchers, in a news release. "The new picture of the Hadean Earth emerging from this work has important implications for its habitability."

The findings reveal a little bit more about the processes that shaped our planet. By understanding how our Earth was formed, scientists can learn a bit more about other planets, as well.

The findings are published in the journal Nature.