Comets and Interstellar Objects Could be Exporting Earth Life Out into the Milky Way

Universe Today | 10/18/2019 | Staff
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For over a century, proponents of Panspermia have argued that life is distributed throughout our galaxy by comets, asteroids, space dust, and planetoids. But in recent years, scientists have argued that this type of distribution may go beyond star systems and be intergalactic in scale. Some have even proposed intriguing new mechanisms for how this distribution could take place.

For instance, it is generally argued that meteorite and asteroid impacts are responsible for kicking up the material that would transport microbes to other planets. However, in a recent study, two Harvard astronomers examine the challenges that this would present and suggest another means – Earth-grazing objects that collect microbes from our atmosphere and then get flung into deep-space.

Study - Exporting - Terrestrial - Life - Out

The study, titled “Exporting Terrestrial Life Out of the Solar System with Gravitational Slingshots of Earthgrazing Bodies“, recently appeared in the International Journal of Astrobiology. The study was authored by Amir Siraj (a Harvard undergrad in astronomy) and Abraham Loeb – the Frank B. Baird Jr. Professor of Science and the Chair of the Astronomy Department at Harvard University.

To break it down, there are several versions of panspermia theory. There’s lithopanspermia, the idea that rocks ejected by impacts are responsible for spreading microbes from planet to planet. Then there is the larger variant, where interstellar asteroids and comets are responsible for distributing life between star systems and maybe even galaxies. Siraj summarized it for Universe Today via email:

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“Traditional theories of panspermia posit that planetary impacts can accelerate debris out of a planet’s gravitational field, and potentially even out of the host star’s gravitational field. Among other issues, this debris is often quite small in size, providing little shielding from harmful radiation for any potentially enclosed microbes during the debris’ journey through space.”

In addition, the traditional approach to panspermia requires a process that both embeds...
(Excerpt) Read more at: Universe Today
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