Bizarre Lava-Covered Planet Is Surrounded by Air That Could Support Life

You are alive right now and able to read this article in part because of Earth's plush atmosphere, a blanket about 60 miles thick. Its most plentiful ingredient is nitrogen, its most beloved oxygen, its most concerning carbon dioxide, and a smattering of other gases. But a similar mix may also envelope a dramatically different planet 40 light-years away from us, according to a new paper published in The Astronomical Journal.

That distant planet, known as 55 Cancri e, has been entrancing scientists since they first spotted it in 2004. It's skewed with respect to its star, its core may be basically a giant diamond, and its surface is covered in lava. It's pretty hard to turn away from a combination like that.

But scientists haven't actually seen the molten rock themselves, nor will they any time soon. Instead, they're basing that hypothesis on what they can measure from here, using a month of data gathered by NASA's Spitzer Space Telescope during the summer of 2013. That instrument measures infrared light, which scientists can then use to understand how temperatures on the planet are changing.

11_15_55cancrie_exoplanet An artist's conception of the planet 55 Cancri e. NASA/JPL-Caltech

The whole lava idea was grounded in the fact that 55 Cancri e is tidally locked, which means the same side of the planet always faces its sun, just like the same side of our moon always faces Earth. When it comes to stars, that's a great recipe for starkly different temperatures on each side of a planet—imagine what would happen to your hometown if the sun either never set or never rose.

Unlike the chill of an eternal night here on Earth, the dark side of 55 Cancri e is just a little less broiling, with temperatures between 2,400 and 2,600 degrees Fahrenheit, compared to about 4,200 degrees on its light side. Scientists had determined last year that that huge temperature difference likely left the sunlit side of 55 Cancri e covered in gigantic lakes of lava, which were frozen on the dark side of the planet.

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Now they've revisited that temperature data to try to understand what's going on above the lava—whether 55 Cancri e has a thick atmosphere, like Earth, or has lost it, like Mercury. They found that the temperature differences between night and day weren't as vast as earlier calculations had estimated. And that, in turn, suggests there's an atmosphere buffering the planet.

The team thinks that the planet's atmosphere, like ours, is also made of gases like nitrogen, oxygen, and water vapor—the sort of thing life on Earth could breathe.

Except, of course, for the bit where it would burn our noses and throats.

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