Found Earth-Size Planets: The Newest, Weirdest Generation
NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. A bumper crop of Earth-size planets (7) huddled around an ultra-cool, red dwarf star could be little more than chunks of rock blasted by radiation, or cloud-covered worlds as broiling hot as Venus.Scientists are pondering the possibilities after this week’s announcement: the discovery of seven worlds orbiting a small, cool star some 40 light-years away, all of them in the ballpark of our home planet in terms of their heft (mass) and size (diameter). Three of the planets reside in the “habitable zone” around their star, TRAPPIST-1, where calculations suggest that conditions might be right for liquid water to exist on their surfaces—though follow-up observations are needed to be sure.
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| Earth-size planets (7) |
NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. A bumper crop of Earth-size planets (7) huddled around an ultra-cool, red dwarf star could be little more than chunks of rock blasted by radiation, or cloud-covered worlds as broiling hot as Venus.
Or they could harbor exotic life forms, thriving under skies of ruddy twilight.
Scientists are pondering the possibilities after this week’s announcement: the discovery of seven worlds orbiting a small, cool star some 40 light-years away, all of them in the ballpark of our home planet in terms of their heft (mass) and size (diameter). Three of the planets reside in the “habitable zone” around their star, TRAPPIST-1, where calculations suggest that conditions might be right for liquid water to exist on their surfaces—though follow-up observations are needed to be sure.
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| TRAPPIST-1 |
Planets are proportionally larger compared to the small stars they orbit. That means small, rocky worlds orbiting the nearest red dwarfs will be primary targets for new, powerful telescopes coming online in the years ahead, both in space and on the ground.
But these are sure to be perplexing planets, with strange properties that must be teased out by careful observation as well as computer simulations. Finding out whether they can support some form of life, and what kind, likely will keep astrobiologists working overtime, perhaps attempting to recreate in the laboratory some of the conditions on these red-tinged worlds.
Would life find a way?
Expert opinion on whether red dwarf planets are suitable for life tends to tick back and forth, “like a pendulum,” said Shawn Domagal-Goldman, a research space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
At the moment, the pendulum is ticking back toward lifelessness. Recent findings suggest life would have an uphill battle on a planet close to a red dwarf, largely because such stars are extremely active in their early years -- shooting off potentially lethal flares and bursts of radiation.
Would life find a way?
Expert opinion on whether red dwarf planets are suitable for life tends to tick back and forth, “like a pendulum,” said Shawn Domagal-Goldman, a research space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
At the moment, the pendulum is ticking back toward lifelessness. Recent findings suggest life would have an uphill battle on a planet close to a red dwarf, largely because such stars are extremely active in their early years -- shooting off potentially lethal flares and bursts of radiation.
Some are born to endless night
Red dwarfs could take their first billion years just to calm down enough to allow any nearby planets to be habitable. And the “habitable zone” around such stars is very close indeed. All seven of the Earth-size planets crowd so close to their star that they complete a single.
That kind of proximity means the planets are probably tidally locked, with one face always turned to the star, the same way our moon presents only one face to Earth. And while red dwarfs are “cool” compared to our sun, they would loom large in the sky of a close, tidally locked planet, perhaps baking the sunward face. The far side, meanwhile, could be trapped in an eternal, frozen night.
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Trapped in an eternal, frozen night |
NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.
The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.
This exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system. Assisted by several ground-based telescopes, including the European Southern Observatory's Very Large Telescope, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.
***NASA’s James Webb Space Telescope (JWST), to be launched in 2018, could help resolve such questions by closely analyzing the atmospheric gases of the TRAPPIST-1 planets. If one of these instruments were to discover water vapor and, say, a combination of oxygen and methane, it could be a strong indication of a potential life-bearing world.
