Discovered: Three Alien Planets That May Support Life

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Three worlds, potentially hospitable for life, have been discovered orbiting a dim, nearby star some 39 light-years away.

Using TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) in Chile, astronomers focused on a star originally named 2MASS J23062928-0502285 to discover these new worlds.  This star is a dim cold red star, now known as TRAPPIST-1, can be found in the constellation Aquarius.

“These kinds of tiny, cold stars may be the places we should first look for life elsewhere in the universe, because they may be the only places where we can detect life on distant Earth-sized planets with our current technology,” study lead author Michaël Gillon, an astronomer at the University of Liège in Belgium, told Space.com.
What’s the closest star to us?
For comparison, the closest star system is about 4.3 light-years from Earth.
TRAPPIST-1 is about 2,000 times less bright than the sun, and one-twelfth the sun’s mass.  It’s a bit less warmer than the sun and less than one-eighth the sun’s width, making it only slightly larger in diameter than Jupiter.  TRAPPIST-1 is considered an ultracool dwarf, a type very common in the Milky Way, making up about 15 percent of the stars near the sun.
How were these worlds discovered?
Scientists were able to spot the three planets after observing TRAPPIST-1 dimming at regular intervals. This is a common way of discovery worlds because the dimming effect of the star is a result of the worlds passing in front of it.
The three discovered planets are only about 10 percent larger in diameter than Earth.  The two innermost planets are about 50 to 90 times closer to their star than our own planet.  However, even though they are very close to their star, the inner two planets receive only four times and two times the amount of radiation that Earth receives.  The third planet, on the other hand, receives less radiation than Earth does.
The small size of the star and its planets’ orbits means the structure of this planetary system is much more similar in scale to the system of Jupiter’s moons.  Further investigation suggests that these close orbits make the planets tidally locked to their star, meaning, that they orbit their star much like our moon orbits Earth–one side always facing its parent.  This means the planets have a permanent dayside and a permanent nightside.
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