Three Earth-Like Planets Found Orbiting Dim Star, And They Could Be Harboring Life

If there’s any chance to find life on other planets, the three new ones just found orbiting a very dim and cold star are our best bet.

The discovery, made by a little telescope called TRAPPIST, has many promising qualities: It could be a sign that even more habitable planets are orbiting other, plentiful dim stars. The three new planets can be easily studied with just a telescope, and because their orbits are pretty short, astronomers can gather the information they need rather quickly.

The three planets were found orbiting an ultracool dwarf star with the same name as the telescope that found it, TRAPPIST-1, CNN reported. It was discovered over the course of 62 nights from September to December last year.

TRAPPIST-1 is barely a star, lying in the constellation Aquarius about 40 light years away. It’s red and too dim to see with the naked eye or amateur telescopes, is half the temperature and tenth the mass of our Sun, shines in the cooler infrared part of the light spectrum, and is about the size of Jupiter, Discovery added.

Astronomers have studied TRAPPIST-1 for years, but lead researcher Michaël Gillon, of the University of Liège in Belgium, wanted to take a closer look and study the space around it. They studied its starlight, minute changes, brightness and found something: shadows, blocking out the light.

“It’s like standing in front of a lamp and throwing a flea across it,” said professor Adam Burgasser of the Center for Astrophysics and Space Science at the University of California San Diego. “It was only a 1% dip in light, but the specific pattern was a good sign of orbiting planets.”

Turns out, they found the well-studied star’s fascinating secret: three planets in its orbit. Burgasser compared the discovery to learning something unexpected about a friend.

“It’s like you’ve known this good friend your whole life and suddenly find out that they’re royalty. What else could we find out about other ‘old friends’ that we previously studied if we went back?”

The three planets they found have some very intriguing characteristics. They are roughly Earth-size. Two of them get four times the radiation as we do from the Sun, putting them in a “habitable zone” for water — the starter ingredient for life. The third planet receives twice the amount of radiation but could still be in the habitable zone as well. Two of them pass in front of the star every one to two days; the third passes in front of the star every four to 72.

“What is super exciting is that for the first time, we have extrasolar worlds similar in size and temperature to Earth—planets that could thus, in theory, harbor liquid water and host life on at least a part of their surfaces—for which the atmospheric composition can be studied in detail with current technology,” Gillon said.

According to Popular Mechanics, astronomers will have a fairly easy time studying their atmospheres because their host star is so dim it doesn’t block their view.

Even more fortuitous is the fact that ultracool dwarf stars like TRAPPIST-1 have been around for much longer than even our own universe — at 1 to 10 billion-years-old — and will live for tens of billions more. In other words, the three planets found have had plenty of time for creatures to evolve, if the conditions are just right.

There is one problem, however. Astronomers found that two of them are tidally locked, which means it’s permanently night on one side and permanently day on the other. That could pose a challenge for potential life forms.

Still, Gillon said that “in theory, all three planets have some habitability potential.”

Astronomers will continue to study the three potentially habitable planets they’ve found. They’ll observe their atmospheres, composition, temperature, and pressure. In the future, they may even be able to look for the biological markers of life.

According to Gillon, these three planets are humanity’s best shot at finding other living creatures out there.

“Systems around these tiny stars are the only places where we can detect life on an Earth-sized exoplanet with our current technology. So if we want to find life elsewhere in the universe, this is where we should start to look.”

[Image via sdecoret/Shutterstock]