First, we have an essentially infinite universe to which we can point our telescopes and try to find alien life; and second, we humans are only familiar with life as we know it.
But on Friday, scientists made a discovery that they believe could dramatically narrow the complex search for life in space. In a paper published in The Astrophysical Journal Letters, the team explains how an Earth-like planet orbits the most common type of star in the universe — an M-type dwarf — and appears to have no atmosphere.
That means it might be possible to conclude that most other terrestrial planets orbiting all other M-dwarf stars have no atmospheres. Therefore, they are unlikely to host life — at least life as we know it.
Michelle Hill, an astrophysicist from UC Riverside and co-author of the study, said in a statement: “The condition of this planet could be a bad sign for planets farther from this type of star. That’s what we’ll learn from the James Webb Space Telescope, which will observe planets like this.”
Hill offered some optimism, however, saying that if a planet is far enough away from an M-type dwarf, it could potentially retain an atmosphere.
Coming back to “finding the unknown,” the team’s findings are critical to this kind of extraterrestrial research, because the best way to accomplish this task is by elimination. Any new data on where these creatures may or may not live could help limit the search.
This land is also the future of Mercury
The name of the sphere without an atmosphere that scientists have pinned on is GJ 1252b.
It’s slightly larger than Earth, which is part of the reason it’s considered “Earth-like,” but it’s much closer to its star than our planet is to the sun, which means it’s extremely hot. Infrared radiation data from GJ 1252b estimates that its daytime temperature reached 2,242 degrees Fahrenheit (1,228 degrees Celsius), which is hot enough to melt gold, silver and copper on its surface.
This excess heat, coupled with the presumed low surface pressure, is what led researchers to believe that GJ 1252b has no atmosphere at all.
“The planet may have more than 700 times more carbon than Earth, but it still wouldn’t have an atmosphere,” Stephen Kane, an astrophysicist at UC Riverside and co-author of the study, said in a statement. It builds up initially, but then tapers off and erodes away.” Plus, the exotic world seems to orbit its star twice every Earth day.
“The pressure from stellar radiation is enormous enough to blow away a planet’s atmosphere,” Hill said.
In our own solar system, the team compared the current state of GJ 1252b to Mercury’s ultimate fate.
Mercury is closer to the sun than Earth, which means it’s as hot as GJ 1252b, and it has a very thin atmosphere. Because of the planet’s heat, those sparse atmosphere atoms quickly escaped into space. Similarly, Earth also loses some of its atmosphere over time, but events like volcanic emissions can replenish the protective layer our home has lost. It also helps that our planet is a little further away from the sun, and therefore cooler.
To the extent that these conclusions about M dwarfs are possible, there are 5,000 stars in the vicinity of Earth alone — most of which are M dwarfs. This would remove a lot of options for finding extraterrestrial life, but we also have to take into account that there are also about 1,000 sun-like stars near our sun. And, this is just our general corner of the universe—a single molecule in the cosmic ocean. So, we humans still don’t know where the aliens are, and locating them is a long road.