We May Actually Stand A Better Chance of Finding Alien Life on Desert Planets
To Boldly Go
Turns out that if there’s a bright center to the universe, we might find life on the planet that it’s furthest from. Eh, eh? Star Wars quote?
Yeah, why don’t we just move along. Scientists who are looking for planets that might support lifeforms generally look for blue-green planets with plenty of water on their surfaces, since water played such an emportant role in the evolution of life on this planet. The problem with water planets, however, is that they’ve got a relatively narrow Goldilocks zone (it’s a thing) in which their water neither freezes nor boils away. Too far from their star and you get Hoth or worse, too close and you wind up with runaway green house conditions where all the water gets so jumpy and high in the atmosphere that its hydrogen splits off and it turns into just oxygen.
But researchers have also recently theorized that life might be just as likely to arise on a planet where there was only some water like Tatooine or Arrakis: desert planets. And, due to their geography, those planets have a much larger Goldilocks zone, and therefore might exist in greater abundance in the universe.
Researcher Yutaka Abe at the University of Tokyo with [planetologist Kevin] Zahnle and their colleagues experimented with a number of simple three-dimensional global climate models for Earth-sized planets. For their simulations of land planets, they left the rotation rates, atmospheric pressures and carbon dioxide levels unchanged but removed oceans and vegetation, leaving behind groundwater locked underneath the surface.
The scientists discovered that a land planet’s habitable zone was three times bigger than an aqua planet’s. “A pale blue dot is not the only model for an Earth-like habitable planet,” they report in their paper, which was recently published in the journal Astrobiology. “The first habitable planet is more likely to be a member of the land planet class than the aqua class.”
…Such a land planet might be much like the fictional planet of Arrakis, “although I don’t think the sandworms sound possible to me,” Zahnle said. “The picture of the equatorial zone being just too hot to live at is there, as well as the poles being habitable. I would actually think that the poles would be a good deal wetter than in ‘Dune’ — there would be more open water at the poles, maybe even small streams and lakes and such.”
Planetary scientist Jim Kasting says that Abe’s research is well done, but that for a desert planet to with water to be identified, there would have to be at least enough water to be seen by our telescopes, and since everyone is already looking for planets with water of any kind, the results are unlikely to change how scientists search for habitable planets.
Zahnle, however thinks that the likelyhood of us not noticing water on desert planets will be offset by the fact that their bigger Goldilocks zone means that they are much more likely to have water and have an orbit closer to their star. The closer a planet is to a star, the easier it is for astronomers to find, as it crosses between us and its star’s light. Zahnle added:
We’re not looking for planets that are habitable permanently, just ones that might be habitable long enough for life. No planet is habitable permanently, not even Earth.
Guess we better keep looking, then! Full article at Physorg.com
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