Webb telescope detects a possible signature of life on a distant world

Joel Achenbach in The Washington Post:

A distant planet’s atmosphere shows signs of molecules that on Earth are associated only with biological activity, a possible signal of life on what is suspected to be a watery world, according to a report published Wednesday that analyzed observations by NASA’s James Webb Space Telescope.

…This possible detection of a biosignature could be “potentially one of the biggest landmarks in the history of science,” Madhusudhan said. “This is the first time humanity has ever seen biosignature molecules — potential biosignature molecules, which are biosignatures on Earth — in the atmosphere of a habitable-zone planet,” he added. The habitable, or “Goldilocks,” zone is the distance from a star that could allow water to remain liquid at the planet’s surface.

K2-18b, which is within our galaxy, the Milky Way, cannot be seen by any telescope as a discrete object. But it has a fortuitous orbit that crosses its parent star as seen from Earth. Such transits dim the starlight ever so slightly, which is how many exoplanets have been discovered. The transits also change the starlight’s spectrum in a pattern that — if observed with instruments on a telescope as advanced as the Webb — can reveal the composition of the planet’s atmosphere.

More here.

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