Around 4 Billion B.C.T., conditions for the creation of life on Earth began to be maximized. Also, around this time, a meteor struck Mars.
When a meteor perhaps as large as a hundred miles in diameter smashed into Mars four billion years ago, the force of the impact re-contoured much of the southern Martian hemisphere. The collision punched a hole in the surface 1,300 miles across and 5 miles deep. The fallout of debris, enough to theoretically deposit a mile-thick layer across the continental United States, stretched 2,500 miles from the basin's center.
The Martian meteor impact of four billion years ago has a bearing on life on Earth because the debris from such impacts wound up landing on Earth and may possibly have contributed to the organic chemistry -- the chemistry of life -- that came to exist.
As of 2012, of the over 53,000 meteorites that have been found on Earth, 99 have been identified as Martian. These meteorites are thought to be from Mars because they have elemental and isotopic compositions that are similar to rocks and atmosphere gases analyzed by spacecraft on Mars.
Some planetary scientists think that the impact of asteroids and comets on Mars sent chunks of Martian rock hurtling into space, where they orbited the sun for millions of years. Finally, some of these bits of Mars came crashing down in Antarctica and other places on Earth. However, the impact on Mars some 4 billion years ago may have led to a more direct contribution of Martian materials to the milieu of what was then the nascent terraforming of Earth.
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