No atmosphere found on a distant Earth-sized world, study finds

CAPE CANAVERAL, Fla. (AP) — The Webb Space Telescope has found no evidence of an atmosphere on one of seven rocky, Earth-sized planets orbiting another star.

Scientists said Monday that doesn’t bode well for the rest of the planets in this solar system, some of which are in the sweet spot to host water and potentially life.

“This is not necessarily a failure” for the other planets, Massachusetts Institute of Technology astrophysicist Sara Seager, who was not part of the study, said in an email. “But we’ll have to wait and see.”

The Trappist Solar System, an oddity with seven planets the size of our own, has drawn astronomers ever since it was spotted just 40 light-years away. That’s close to cosmic standards; a light year is about 5.8 trillion miles. Three of the seven planets are in the habitable zone of their star, which makes this star system even more attractive.

The NASA-led team reported that little to no atmosphere exists on the innermost planet. The results were published Monday in the journal Nature.

The lack of an atmosphere would mean no water and no protection from cosmic rays, said principal investigator Thomas Greene of NASA’s Ames Research Center.

As for the other planets orbiting the small, faint Trappist star, “I would have been more optimistic about the others” having atmospheres if this one did, Greene said in an email.

If rocky planets orbiting ultracool red dwarf stars like this one “turn out to be a dud, we’ll have to wait for Earths around Sun-like stars, which could be a long wait,” said MIT’s Seager.

Because the innermost planet of the Trappist system is bombarded by solar radiation — four times more than Earth receives from our sun — the extra energy may be the reason there is no atmosphere, Greene said. His team found temperatures there reaching 450 degrees Fahrenheit (230 degrees Celsius) on the side of the planet that constantly faces its star.

Using Webb, the largest and most powerful telescope ever sent into space, American and French scientists were able to measure the change in brightness as the innermost planet moved behind its star and calculate the amount of infrared light emitted. for the planet

The change in brightness was minuscule since the Trappist star is more than 1,000 times brighter than this planet, so Webb’s detection “is itself a major milestone,” the European Space Agency said.

More observations of not only this planet, but the others in the Trappist system are planned. Looking at this particular planet at another wavelength could uncover an atmosphere much thinner than our own, although it seems unlikely it could survive, said Taylor Bell of the Bay Area Environmental Research Institute, who was part of the study.

Further research could still uncover some sort of atmosphere, even if it’s not exactly like what’s seen on Earth, said Michael Gillon of the University of Liège in Belgium, who was part of the team that discovered the first three Trappist planets in 2016. He did not participate in the latest study.

“With rocky exoplanets, we are in uncharted territory,” as scientists’ understanding is based on the four rocky planets in our solar system, Gillon said in an email.

Launched in late 2021 to an observation post 1.6 million kilometers (1 million miles) away, Webb is considered the successor to the Hubble Space Telescope, which has orbited Earth for more than three decades.

In the past, Hubble and the Spitzer Space Telescope have searched the Trappist system for atmospheres, but without definitive results.

“It’s just the beginning, and what we can learn with the inner planets is going to be different from what we can learn from the others,” Julien de Wit of MIT, who was not involved in the study, said in an email.

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