Astrobiology: Life Must Form Quickly on Some Planets

Planets around small mass stars may only have a billion-year window during which life can form. This is the implication of research into the tidal forces that can pull a planet into a tighter orbit around a star.

The so-called habitable zone around a star is loosely defined as planetary orbits in which water would be liquid, not vapor or solid, on the planets' surface. These orbits are closer-in for smaller (less bright) stars.

However, habitability is not a permanent property of a planet.

"For some planets around low mass stars, they are not going to hang around in the habitable zone forever," says Rory Barnes of the Lunar and Planetary Institute at the University of Arizona. "They are going to be pulled out."

The pulling is due to tidal forces that arise because the gravitational attraction between planet and star is not uniform over their surfaces.

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Later in the article, Barnes discusses that if life takes root on a planet, eviction from the habitable zone may not bee the end. Life may adapt, and adapt its environment to keep a planet habitable.

I've often wondered about this and had many an interesting conversation with friends.

If we are to survive as a species, the the inevitable fact is that we will eventually have to leave and find a new planet. Perhaps Mars first... then some of the moons orbiting the outer planets - but what then?

It makes me wonder how many civilizations have already faced this dilemma. Perhaps the ET's that visit this planet have already survived such a situation?

They say necessity is the mother of creation and perhaps that's also why they developed ships capable of galactic travel? Just a theory....


IRM