Newly discovered exoplanets may be best hope yet for finding alien life.

Scientists have discovered three new planets that may be the most likely location for alien life yet discovered. 

The newfound planets circle a star just 40 light-years away from Earth. The findings were presented Monday in a new study in the journal Nature Geoscience

The three worlds all circle the ultracool dwarf star TRAPPIST-1, and all are just about the size of Earth. It’s even possible that the planets could be orbiting in the “habitable zone” of the host star — orbits that would allow liquid water to be sustained on the planet's surface.

These worlds, however, are no Earth twins, according to the study. They are the first planets found in orbit around an ultracool dwarf star, a type of long-lived stellar object far cooler and dimmer than the sun.

In fact, if you were to stand on the surface of TRAPPIST-1d, which is considered the most potentially habitable of the three planets, you would probably see a huge, red star in the sky. 

According to astronomer Michaël Gillon, a researcher at the University of Liege in Beligum and co-author of the new study, you would be able to look directly at the star without sunglasses.

“You can see, close to the star, the two other planets. They are big enough for you to see some detail of their surface or of their atmosphere. Now let's look where you stand,” Gillon told Mashable via email.

“The landscape is reddish, as the star does not emit bluer light. You are on a ground made of rocks, or of ice. Or you are on a huge reddish ocean. Maybe there [are] big volcanoes in eruption in the background," he said. 

"Maybe there is some creature coming closer and closer to you. We can't say. Not yet.”

Earth-sized exoplanets

The question of alien life notwithstanding, Gillon and his colleagues do know a few important things about the new exoplanets.

For one thing, it's clear that the three planets orbit quite close to their star. Two make a full circuit of their star once every 1.5 days and 2.4 days, respectively, while the orbit of the third planet isn’t well defined yet. 

Although it sounds like the planets would fry by being located so close to the star, they’re actually pretty comfortable.

Because the star is so dim, its habitable nearer to it than it is for brighter stars, such as the sun.

“On the outer planet, the temperature should be somewhere between 200 Kelvin [minus-100 degrees Fahrenheit] and 300 Kelvin [80 degrees Fahrenheit]," Gillon said. "Pretty cold, or perfect for a barbecue. On the two inner planets, the dayside is hot, above 350 Kelvin [170 degrees Fahrenheit]." 

“But a part of the night side could be close to 300 Kelvin, fine for spending some holidays there.”

Allowing alien civilizations to grow

Stars like TRAPPIST-1 can be very long-lived. Unlike more massive stars, ultracool dwarf stars are able to remain in a stable state for billions upon billions of years without running out of fuel to burn. That long-lived system could be just what life needs to thrive.

The stability of this star is important, since civilizations of intelligent life likely take a long time to grow up.

"They could potentially be very nice places to be for a civilization for a long time," NASA's Steve Howell, project scientist for the K2 mission, an exoplanet hunting telescope, told Mashable in an interview. Howell was not involved in the new study.

"You would get civilizations that could last for a long time, or evolution of life could take a long, long time but it would have all that time before the star does something crazy," Howell said.  

Ultracool dwarfs aren’t perfect, however. These types of stars can shoot off extreme flares that send radiation off into their systems, possibly impacting planets the way the most severe solar storms do when they slam into Earth’s magnetic field.

Hunting for life

One day, maybe in the not too distant future, scientists might actually be able to say whether there are creatures likely to be living on those worlds.

Scientists have found multiple exoplanets that could potentially be habitable, but these three worlds around TRAPPIST-1 are particularly tantalizing because of their proximity to Earth.

“But, unlike all previously found Earth-like exoplanets, e.g. Kepler-186f, these new planets are well-suited for detailed study, so we will be able to learn a lot about them in the near-future,” Gillon said.

And researchers are already expecting plenty of follow-up observations.

"At 40 light-years away, my guess is that this particular planet system will now be the most studied planet system until the next cool one comes along," Howell said.

Howell expects that the Hubble Space Telescope will take a look at the three newfound planets, and the K2 mission — which is responsible for finding multiple exoplanets itself — will be able to take a look at the planetary system within the next year as part of an observing campaign.

The Hubble should even be able to tell if there’s a significant amount of water in the atmospheres of the planets.

NASA’s James Webb Space Telescope (JWST), expected to launch in 2018, will also have the ability to check out the TRAPPIST-1 system in great detail.

“With JWST, we will really probe the atmosphere in detail,” Gillon said. “The study of these fascinating planets is just beginning!”