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How One Barren Planet Could 'Dramatically Narrow' the Search for Alien Life

We still don't know where aliens are, but we're learning where they probably aren't.

An artist's illustration of a planet's atmosphere being blown away by a nearby star.
NASA

In physics, a good deal of time is dedicated to searching for something without knowing what you're searching for. A shot in the dark, you might say. This paradoxical task summarizes some of the most massive scientific endeavors, like the hunt for dark matter and antimatter and the quest to complete the Standard Model of Particle Physics

But it's especially present in our pursuit of alien life. 

First of all, we have an essentially infinite universe upon which to point our telescopes in an attempt to find extraterrestrial beings, and second, we're only familiar with life as we know it. Of course, aliens could be exactly like us. Or… they could be gooey monsters made of methane and intangible brains stuck in the fourth dimension. 

Though last week, scientists made a discovery they believe could "dramatically narrow" the complicated search for space creatures. In a paper published in The Astrophysical Journal Letters, the team explains how an Earth-like planet orbiting the most common type of star in the universe, an M dwarf, seems to have no atmosphere. 

What this means is perhaps we can conclude that most other Earth-like planets orbiting all those other M dwarfs don't have atmospheres either. 

Thus, they'd be unlikely to host life -- well, life as we know it, at least. 

"It's possible this planet's condition could be a bad sign for planets even further away from this type of star," Michelle Hill, an astrophysicist at the University of California Riverside and co-author of the study, said in a statement. "This is something we'll learn from the James Webb Space Telescope, which will be looking at planets like these."

Hill does offer some optimism, however, stating that if a planet is far enough away from an M dwarf, it could "potentially retain an atmosphere." 

Getting back to that "scouring for the unknown" bit, the team's finding is crucial for this sort of research in extraterrestrial studies because the best way to go about such a task is by process of elimination. 

Any new data about where these beings may live -- or may not live -- is instrumental in constraining the search.

This land is also the future of Mercury

The atmosphere-less orb the study scientists zeroed in on goes by the name of GJ 1252b. 

It's slightly larger than Earth, which is part of why it's considered "Earth-like," but it's much closer to its star than our planet is to the sun, meaning it's incredibly hot. It's so hot, in fact, that GJ 1252b's infrared radiation data estimated its daytime temperature to reach 2,242 degrees Fahrenheit (1,228 degrees Celsius). That's scorching enough to literally melt gold, silver and copper on its surface. 

This excessive heat, combined with a presumed low surface pressure, is what led the researchers to believe GJ 1252b has simply no atmosphere. 

"The planet could have 700 times more carbon than Earth has, and it still wouldn't have an atmosphere. It would build up initially, but then taper off and erode away," Stephen Kane, an astrophysicist at UC Riverside and co-author of the study, said in a statement. Also, the foreign world appears to orbit its star two times for every Earth day. 

"The pressure from the star's radiation is immense, enough to blow a planet's atmosphere away," Hill said. 

A flaring red star is seen toward the top left and to the botom right is a planet with its atmosphere being stripped.

An artists's impression of a red dwarfs, or M dwarf, that's stripping a nearby planet's atmosphere over time, making the surface inhospitable.

NASA/ESA/STScI/G. Bacon

In our own solar system, the study team compares the current state of GJ 1252b to the ultimate fate of Mercury. 

Mercury is much closer to the sun than Earth, meaning it's really hot like GJ 1252b, and it has a very thin atmosphere. Due to the planet's intense heat, those sparse atmospheric atoms quickly escape into space. In a similar vein, Earth also loses some atmosphere over time, but events like volcanic emissions sort of replenish our home's lost shield. It also helps that our planet is a bit farther from the sun, and therefore cooler.

In terms of how far these conclusions about M dwarfs may reach, (assuming the worst, that planets around such stars are, indeed, atmosphere-less), there are 5,000 stars in Earth's vicinity alone – most of them M-dwarfs. That'd delete a lot of options for finding extraterrestrial life, but we also have to consider that there are about 1,000 stars similar to the sun in our solar neighborhood too. 

And, that's just our general corner of the universe -- a single molecule in the cosmic ocean. 

So, yes, we still don't know where aliens are, and locating them is a long road ahead. But at least we now know where they probably aren't.