Alien Life Could Have ‘Seeded’ Earth and Other Planets

If life begins on a few planets and then spreads through space to other worlds, then planets with life on them should be found in a clumpy pattern around the galaxy, in roughly spherical regions separated by voids. “If the Earth is seeding life, or vice versa, there’s a good chance immediate neighbors will also have signs of life”. This may happen should a planet, rich with life, be hit by a massive asteroid impact; pieces of that planet’s crust will be propelled into space and any life contained within those samples may be transplanted to another world.

It has been shown, by the presence of Mars rocks on Earth, that chunks of material can travel from planet to planet. A team of U.S. astrophysicists proposes a new strategy to answer this question based on the principle that alien life which arose via spreading – in a process called panspermia – will exhibit more clustering than life which arose spontaneously.

Not that there’s any reason to expect that life would resemble anything we see on Earth.

The latest findings don’t say whether or not this “drifting” life is possible. Well, like a common cold, the spread would appear viral. If the seed reaches a habitable planet, it can take root and form its own civilization.

Loeb adds that life could spread from one host star to another one in a pattern that is similar to an outbreak of an epidemic where the Milky Way can become infected with pockets of life.

“It’s not that different from an epidemic”, says Lin, an undergraduate with the Harvard-Smithsonian Center for Astrophysics and lead author of the study, which was accepted by the Astrophysical Journal.

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The Milky Way could be littered with bubbles of life. 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.

Future bio-signatures could confirm their statistical predictions, even if the incidence of life is relatively low, but we still need some experimental proof.

The researched have made the hopeful statement that we might soon be able to distinguish a pattern of these “bubbles of life” and track down where they were headed, though certain important factors remain unknown. Has it spread throughout the solar system or even to other stars?