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Cool stars and comfy planets

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A star and seven planets

Meet the seven planets of TRAPPIST-1 in this artist’s impression.
Image: NASA/JPL-Caltech

Is there life on other planets? It may seem like we’re alone in the universe, but there’s still hope. The race is on to find signs of life on Earth-like planets, which have atmospheres and liquid water on the surface.

Recently, it was announced that scientists have discovered seven planets orbiting nearby star TRAPPIST-1, each with the possibility of liquid water.

TRAPPIST-1 is a red dwarf star, much smaller than our sun. As red dwarfs are so small, the reactions that power them are slower than in our star. Just like turning down an old-fashioned light bulb, the light is dimmer, cooler and red in colour.

To have liquid water, a planet needs just enough heat to melt ice, without boiling it away. Red dwarfs don’t make a lot of heat compared to our sun. Luckily, the planets detected are very close to TRAPPIST-1 at a distance that might be just right for liquid water.

Sadly, this closeness might not be good for the possibility of life. It means TRAPPIST-1’s planets are probably tidally locked to the star, so one side would always be in daytime, and the other side eternally night. Plus young red dwarfs often flare up, emitting high powered x-rays that could blow away a nearby planet’s atmosphere.

However, scientists remain optimistic. And we don’t have long to wait for more information. The James Webb Space Telescope is set to be launched in 2018. Looking for signs of life on distant planets will be one of this new telescope’s most important missions.

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