Chris McKitterick (mckitterick) wrote,
Chris McKitterick

Astro-Porn of the Day2: Gliese 581g, or Earth-Like Exoplanet Discovered!

I just learned from my pest-control dude ("Schendelize 'em!") that we've discovered the first truly habitable (by humans) exoplanet, Gliese 581g. It's Earth-sized (three Earth masses) and orbits in the middle of its star's habitable zone, where liquid water could exist on the planet's surface. This puppy is the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one. Here's a close-up, photographed by the Vanguard generation ship, launched 3000 years ago from the island-nation of Atlantis:

Click the image to see the story. NOTE: The thing about Atlantis and Vanguard might not be true.

"New Earth," as the Vanguardians call it, is only one of two new planets discovered orbiting the nearby red dwarf star, named Gliese 581 by Earth-humans. This brings the tally of known planets around this star to 6, the most yet discovered in a planetary system other than our own. As in our Solar System, the planets around Gliese 581 have nearly circular orbits, though 581g (the Earth-like one) has an orbital period (aka "year") of only 37 days - in really close for good ol' Sol, who'd burn it to a crisp, but Gliese 581 is a feeble red dwarf star, so it's comfortably warm and has, I'm sure, the most amazing sky of any Earth-like planet, being so close to its parent. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere. Because it's tidally locked (doesn't rotate), the 581g-ans who live on the side facing away from the sun live in cyberpunkey perpetual night, gambling their lives against AI overlords. And stuff.

Money shot: "The fact that we were able to detect this planet so quickly and so nearby," sez Steven Vogt, who leads the Lick-Carnegie Exoplanet Survey (shut up your inner 12-year-old), "tells us that planets like this must be really common. If these are rare, we shouldn't have found one so quickly and so nearby," Vogt said. "The number of systems with potentially habitable planets is probably on the order of 10 or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that's a large number. There could be tens of billions of these systems in our galaxy."

Tens of billions of Earth-like planets in our galaxy, alone. Ponder that.

Here's the paper.

We live in amazing times!

Tags: age of wonders, astronomy

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