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Some TRAPPIST-1 planets may be water worlds

Water is a sign of possible life. Too much water may prevent us from finding it

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5:53pm, March 19, 2018
TRAPPIST-1 planets

WATER WORLDS  The TRAPPIST-1 system, with seven Earth-sized planets orbiting a dwarf star, has captured the attention of scientists hunting for life outside the solar system. New estimates of the planets’ composition indicates that several are enveloped in water and ice.

There’s so much water on some of TRAPPIST-1’s seven Earth-sized planets that any life lurking there might be difficult to detect.

New estimates of the makeup of these potentially habitable worlds suggests that two of them are more than half water, by mass, researchers report March 19 in Nature Astronomy. Earth, by comparison, is less than 0.1 percent water.

TRAPPIST-1’s planets are so wet that most of the water probably isn’t even liquid, but ice formed under high pressure, says Cayman Unterborn, an exogeologist at Arizona State University in Tempe. That would change the chemistry happening on the planet in a way that could make any signs of life tricky to distinguish from geochemical processes.

TRAPPIST-1 is a cool, dim star about 39 light-years from Earth. Since the

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