TRAPPIST-1 Planets Discovery Explained: What Are Exoplanets, and Is There Life?

This artist's concept allows us to imagine what it would be like to stand on the surface of the exoplanet TRAPPIST-1f, located in the TRAPPIST-1 system in the constellation Aquarius.
This artist's concept allows us to imagine what it would be like to stand on the surface of the exoplanet TRAPPIST-1f, located in the TRAPPIST-1 system in the constellation Aquarius.  Caltech manages JPL for NASA

Is anyone out there? Seven possibly life-sustaining, Earth-size planets were discovered revolving around the tiny TRAPPIST-1 star, according to a new study published in the journal Nature on Wednesday, February 22.

The solar system is just 39 light-years away from our own system, which, in the grand scale of things, is relatively close. “Thirty-nine light-years might seem like a long distance, and we don’t have any way of getting there, but it’s actually really close when you think about the scale of the galaxy,” the Washington Post’s Sarah Kaplan explained. “The Milky Way is 100,000 light-years wide, and 39 light-years is practically our next-door neighbor.”

The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial, according to research published in 2017 in the journal Nature. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it.
The seven planets of TRAPPIST-1 are all Earth-size and terrestrial, according to research published in 2017 in the journal 'Nature.' The TRAPPIST-1 star is an ultracool dwarf star in the constellation Aquarius, and its planets orbit very close to it. Caltech manages JPL for NASA

The discovery of TRAPPIST-1’s seven planets is extra significant because they all happen to fall into what’s known as the “temperate zone,” or consisting of a climate that is able to sustain water and, therefore, life.

All seven planets discovered in orbit around the red dwarf star TRAPPIST-1 could easily fit inside the orbit of Mercury, the innermost planet of our solar system. In fact, they would have room to spare. TRAPPIST-1 also is only a fraction of the size of our sun; it isnt much larger than Jupiter. So the TRAPPIST-1 systems proportions look more like Jupiter and its moons than those of our solar system.
All seven planets discovered in orbit around the red dwarf star of TRAPPIST-1 could easily fit inside the orbit of Mercury, the innermost planet of our solar system. In fact, they would have room to spare. The TRAPPIST-1 star is also only a fraction of the size of our sun; it isn't much larger than Jupiter. So the TRAPPIST-1 system's proportions look more like Jupiter and its moons than those of our solar system. Caltech manages JPL for NASA

“The discovery gives us a hint that finding a second Earth is not just a matter of if, but when,” Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA, told the U.K.’s Telegraph

TRAPPIST stands for Transiting Planets and Planetesimals Small Telescope, the telescope that identified the tiny parent star and its seven planets. According to the Telegraph, part of the reason why the planets fall into the temperate zone is their parent star is so much smaller (one-tenth the size of our solar system’s sun) and therefore is less fiery. (Mercury, for instance, has a wide-swinging range between -279 degrees Fahrenheit at its lowest and 801 degrees Fahrenheit at its highest, and would thus never be able to sustain liquid water or life.)

This illustration shows the seven TRAPPIST-1 planets as they might look as viewed from Earth using a fictional, incredibly powerful telescope. The sizes and relative positions are correctly to scale
This illustration shows the seven TRAPPIST-1 planets as they might look viewed from Earth using a fictional, incredibly powerful telescope. The sizes and relative positions are depicted correctly to scale. Caltech manages JPL for NASA

Astronomers have found other exoplanets before (the first was discovered in 1992), but this marks the first time they have found so many terrestrial planets orbiting a single star. Even if it turns out that they don’t host aliens, TRAPPIST-1 will still give planetary scientists a new way to understand how solar systems are formed.

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