Giant Moon-forming impact blew off Earth's atmosphere

The giant impact which formed the Moon may have also blown off the Earth's atmosphere, scientists, including one of Indian-origin, have proposed.
The lunar body came into existence after several planet-size space bodies smashed into the early Earth one after the other, researchers said.
Scientists, until now, believed it was unlikely that the early Earth could lose its atmosphere because of a giant Moon-forming impact.
However, the new research argues that this may have been possible, 'SPACE.Com' reported.
The study is based on recent research showing that at its infancy Earth had magma oceans and was spinning so rapidly that a day was only two or three hours long.

"Part of the Earth remembers its infancy, and it's giving us clues to the stages of growth of the Earth," said planetary scientist Sarah Stewart, a professor at Harvard University.

The team based the research on two recent studies: One argues that the Moon is actually a giant merger of bits and pieces of our Earth, partially destroyed by a catastrophic collision with a space body 4.5 billion years ago.
The Earth had a two- or three-hour day back then and the impact made it throw off enough material to coalesce into what became our satellite, making it the Earth's geochemical twin, Sarah said.

This ultra-rapid spin is one of the important conditions necessary to make the atmospheric loss theory work, she said.
The other criterion is the presence of terrestrial magma oceans - and this hypothesis has now got support thanks to new data obtained from volcanoes, researchers said.
Researchers Jonathan Tucker and Sujoy Mukhopadhyay sampled elements from volcanoes in Iceland, which have rocks that are among the oldest on Earth and thus retain the geochemical signatures of the Earth's so-called lower-most mantle, closest to the planet's core.
They also looked at elements found in volcanoes that sample the upper mantle, such as mid-ocean ridge basalts at the bottom of the Atlantic, the report said.

They found that elements in the deep mantle that retain a very ancient chemistry, from the times of the Earth's formation, are very different from those in the upper mantle found today.