Alien Life Could Have 'Seeded' Earth and Other Planets

Could aliens have started life on Earth? That's a good question and now, researchers are saying it's possible. Scientists have found that if life can travel between the stars, a process called panspermia, it would spread in a characteristic pattern that we could possibly identify.

"In our theory clusters of life form, grow, and overlap like bubbles in a pot of boiling water," said Henry Lin, lead author of the new study, in a news release.

The researchers found that there are two basic ways for life to spread beyond its host star. The first would be via natural processes such as gravitational slingshotting of asteroids or comets. The second would be for intelligent life to deliberately travel outward.

The model assumes that seeds from one living planet spread outward in all directions. If a seed reaches a habitable planet orbiting a neighboring star, it can take root. Over time, the result of this process would be a series of life-bearing oases dotting the galactic landscape.

"Life could spread from host star to host star in a pattern similar to the outbreak of an epidemic," said Avi Loeb, one of the researchers. "In a sense, the Milky Way would become infected with pockets of life."

If we detect signs of life in the atmospheres of alien worlds, the next step will be to look for a pattern. For example, in an ideal case where the Earth is on the edge of a "bubble" of life, all of the nearby life-hosting worlds we find will be in one half of the sky and the other half will be barren.

The latest findings don't say whether or not this "drifting" life is possible. They just show the patterns that spreading life might take. If this pattern is true, though, it's very possible that life came from another world to Earth, which may mean that we could potentially track down that world in the future.

The findings are published in the journal Astrophysical Journal Letters.

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