Astronomers have discovered a system of seven Earth-sized exoplanets orbiting a nearby star, at least three of which sit in the temperate “habitable zone” where liquid water could exist.The proximity of the planets’ host star, known as TRAPPIST-1, to our own — just 39 light years away — immediately makes this system one of the best places to look for life outside our solar system.And a Canadian instrument aboard the James Webb Space Telescope, a next-generation space telescope set to launch next year, will be positioned to do just that. “We’re very excited here in Canada,” said Université de Montréal professor René Doyon, the principal investigator of the instrument, NIRISS, which was given to the telescope project by the Canadian Space Agency. “We will be among the first to actually study these habitable-zone exoplanets,” Doyon said, using the term for planets that orbit stars outside our solar system.TRAPPIST-1 is an ultra-cool dwarf star. Small, dim stars like this are great candidates for detecting new Earth-sized planets, because when one passes in front of its star, temporarily blocking it — a “transit” — the starlight reaching Earth dips more dramatically than it would for a very big, bright star like the sun. Using a ground-based telescope in Chile, a team led by Michaël Gillon, an astronomer at the Université de Liège in Belgium, reported last year that TRAPPIST-1 had three Earth-sized exoplanets. But when they followed up and looked more closely at the system using NASA’s Spitzer space telescope and other instruments, they discovered the dwarf star actually hosted seven.“It’s the first time that so many planets of this kind are found around the same star,” Gillon said. A paper describing the system was published in the journal Nature.TRAPPIST-1 may be small and dim, but because the planets all orbit ...
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