1. New Clues to Compositions of TRAPPIST-1 Planets

    This artist's concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets' diameters, masses and distances from the host star, as of February 2018.
Credits: NASA/JPL-Caltech Image credit: None
    This artist's concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets' diameters, masses and distances from the host star, as of February 2018. Credits: NASA/JPL-Caltech

    The seven Earth-size planets of TRAPPIST-1 are all mostly made of rock, with some having the potential to hold more water than Earth, according to a new study published in the journal Astronomy and Astrophysic. The planets’ densities, now known much more precisely than before, suggest that some planets could have up to 5 percent of their mass in water — which is 250 times more than the oceans on Earth.

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    Source: [NASA JPL]