Just Right Goldilocks

by Wayne Ferrier

AA_NASA IMAGE exoplanet In the constellation of Libra is Zarmina’s World, the first habitable planet discovered outside our own solar system. Zarmina’s World orbits Gliese 581, a red dwarf star that is about a third the mass of our sun. It's about 120 trillion miles away, which in the scheme of things is right smack in our neighborhood. Using current technology, it would only take us several generations to make it there—not outside the realm of our current capabilities. The two scientists who discovered Zarmina’s World, Steven Vogt and Paul Butler, calculate that there could be as many as one out of five or ten stars in the universe that might have Earth-like planets in the habitable zone. With an estimated 200 billion stars in the Milky Way alone, there could be as many as 40 billion planets that could potentially harbor life here. However, this is all very speculative just how common these Earth-like planets really are in the Milky Way.

Temperatures on Zarmina—for convenience sake let’s call it Zarmina—get as hot as 160 degrees and as cold as 25 degrees below zero, but in between “it’s shirt-sleeve weather,” says co-discoverer Steven Vogt of the University of California at Santa Cruz. And the low-energy dwarf star Gliese 581, Zarmina’s sun, ought to continue to shine for billions of years, a lot longer than our sun will, which increases exponentially the likelihood that life could possibly develop there.

It's unknown if there is water on Zarmina, and what kind of atmosphere it actually does have. But because conditions there are ideal for liquid water, and because there always seems to be life on Earth where there is water, there is a lot of excitement being generated about the discovery of this Earth-like planet. But that’s the catch—does it have liquid water and the kind of atmosphere that really would make it really, really habitable?

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