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2 Earth-Sized Exoplanets Confirmed to be Rocky, Could Harbor Alien Life

Jul 21, 2016 01:55 AM EDT
Terrestrial Planets
Artist's view of planets transiting a red dwarf star in the TRAPPIST-1 system.
(Photo : NASA, ESA, and STScI)

Astronomers have confirmed that two of the three exoplanets orbiting a dim, cold, red star named TRAPPIST-1are rocky and have comparatively thin atmosphere, making it more likely to support life.

According to a report from, the TRAPPIST-1 is an "ultracool dwarf" about 39 light years away from Earth. It is said to be 2,000 times dimmer than the sun and a bit less than half as warm as the sun.

Previous research pointed out that some regions of the three exoplanets have regions with the right temperature to hold liquid water, suggesting that it might be capable of supporting life based on their size and temperature. However, researchers at that time are unsure if the three planets are rocky just like Earth.

Now, researchers have confirmed that the two innermost exoplanets of TRAPPIST-1 are primarily rocky planets using NASA's Hubble Telescope.

In a rare event on May 4, TRAPPIST-1c and TRAPPIST-1b passed in front of their star at the same. The researchers pointed the Hubble telescope at TRAPPIST-1 to capture the rare double transit and study the atmospheric properties of the two exoplanets at the same time.

Their findings, described in a paper published in the journal Nature, revealed that the dips in TRAPPIST-1's light during the double transit did not vary significantly, suggesting that two worlds have compact atmosphere like other rocky planets.

However, the researchers are still not certain on the specific atmosphere of TRAPPIST-1c and TRAPPIST-1b.

"The plausible scenarios include something like Venus, with high, thick clouds and an atmosphere dominated by carbon dioxide, or an Earth-like atmosphere dominated by nitrogen and oxygen, or even something like Mars with a depleted atmosphere. The next step is to try to disentangle all these possible scenarios that exist for these terrestrial planets," explained Julien de Wit, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences and first author of the planet, in a statement.

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