JWST just confirmed its first Earth-sized exoplanet: ScienceAlert

JWST just confirmed its first Earth-sized exoplanet: ScienceAlert

JWST just confirmed its first Earth-sized exoplanet: ScienceAlert

Since its launch in December 2021, the James Webb Space Telescope (JWST) has been breaking records.

Now the instrument has spotted its first planet around a star other than ours i with an estimated diameter of about 99 percent of the Earth’s diameter looks a bit familiar.

Observations from NASA’s Transiting Exoplanet Survey Satellite (TESS) indicated the planet was there, but now the high-resolution images offered by the near-infrared spectrograph (NIROSpec) aboard JWST have confirmed this.

Despite the similarity in size, the planet is believed to be much hotter than our home planet, orbiting the red dwarf close enough to orbit it in just two days.

“There is no doubt that the planet is there,” says astronomer Jacob Lustig-Yaeger of the Johns Hopkins University Applied Physics Laboratory in Maryland. “Webb’s immaculate data confirmed this.”

This newly discovered object is located 41 light-years away in the constellation of Octanes and is designated LHS 475 b. As with other exoplanets, it was spotted by observing the shadow that forms as it passes in front of its star.

What makes JWST unique is that it can look at transmission spectra; an assortment of wavelengths of light filtered around a planet that can reveal features of its atmosphere.

Transmission spectrum readings
The readings suggest that LHS 475 b does not have a methane-dominated atmosphere. (NASA/ESA/CSA/L. Hustak (STScI))

For now, we don’t have enough data to tell us what kind of atmosphere LHS 475 b has, if any. Astronomers are so far sure it lacks a dense, methane-rich atmosphere like that surrounding Saturn’s moon Titan.

“The telescope is so sensitive and the data so precise that we could easily detect several different particles, but we haven’t seen much yet,” says astrophysicist Ortiz Ceballos of the Harvard-Smithsonian Center for Astrophysics in Massachusetts.

But they cannot rule out a shallow atmosphere consisting of pure carbon dioxide.

The added precision offered by JWST means researchers can look for stars and planets that are much smaller. Typically, telescopes look for exoplanets larger than Jupiter, about 11 times wider than Earth.

Information is also being gathered at a rapid pace: JWST only needed two transits (or flybys) to identify LHS 475 b and some of its features. Further reading should tell us more about what we are dealing with here.

We also see JWST creating absolutely stunning pictures from space, thanks to the sensitivity of its onboard instruments – and it’s only been operating for just over a year. There’s still a lot ahead of us.

“These first observations of an Earth-sized rocky planet open the door to many future opportunities to study the atmospheres of rocky planets with Webb,” said Mark Clampin, director of the Astrophysics Division at NASA Headquarters in Washington, DC.

“Webb is bringing us closer and closer to a new understanding of Earth-like worlds beyond our solar system, and the mission is just getting started.”

The findings were presented at the meeting of the American Astronomical Society on Wednesday, January 11, 2023.

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