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Worlds without end: New data from Hubble suggests that two rocky exoplanets only 40 light years away have atmospheres more similar to Earth’s than to that of gas giants.
Specifically, they discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds. “The lack of a smothering hydrogen-helium envelope increases the chances for habitability on these planets,” said team member Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. “If they had a significant hydrogen-helium envelope, there is no chance that either one of them could potentially support life because the dense atmosphere would act like a greenhouse.”
The actual make-up of these atmospheres remains unknown. Also, the central star, a red dwarf, is estimated to be about a half billion years old. Both the star’s make-up — red dwarfs are not as rich in elements as a G-type sun — and age do not provide much margin for the development of life.
Nonetheless, the new data increases again the likelihood that we will eventually find habitable worlds orbiting other stars, and we will find them in large numbers.