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Webb telescope reveals distant planet’s atmosphere in unprecedented detail

The James Webb Space Telescope has provided readings of “a full menu of atoms, molecules and even signs of active chemistry and clouds" of the distant planet WASP-39 b.

James Webb Space TelescopeThe list of discoveries made using JWST's latest observations includes the first detection of sulphur dioxide on an exoplanet. (Image credit: Melissa Weiss/Center for Astrophysics | Harvard & Smithsonian)

The James Webb Space Telescope’s (JWST) latest observations of WASP-39 b, a distant “hot Saturn” planet, has revealed the presence of sulphur dioxide on the planet, among other details.

While JWST and other space telescopes have found the presence of isolated molecules on the planet, the latest readings provide “a full menu of atoms, molecules and even signs of active chemistry and clouds,” according to Harvard Smithsonian Center for Astrophysics.

“The clarity of the signals from a number of different molecules in the data is remarkable. We had predicted that we were going to see many of those signals, but still, when I first saw the data, I was in awe” says astronomer Mercedes López-Morales, in a press statement. López-Morales works at the Harvard Smithsonian Centre for Astrophysics and contributed to a series of new studies that are available on the preprint server arXiv.

Apart from helping scientists understand more about the chemical composition of the planet, the latest JWST observations also give a hint about how the cloud on the planet might consist of broken-up patches instead of forming a single, uniform blanket above the planet.

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The scientists observed WASP-39 b with many different  instruments to get a “broad swath of the infrared spectrum and a panoply of chemical fingerprints inaccessible until JWST,” according to Natalie Batalha, an astronomer at the University of California, Santa Cruz.

The list of discoveries made using the latest observations include the first detection of sulphur dioxide on an exoplanet. The molecule is produced on the planet by chemical reactions that are triggered by high-energy light from the planet’s parent star, in a process similar to how the Earth’s ozone layer is created.

Some of the other atmospheric constituents detected by JWST include sodium, potassium, and water vapour. These findings confirm previous observations made by space and ground-based telescopes, while also finding additional water features that were not seen before.


With temperatures hovering around 8,800 degrees Celsius and an atmosphere that is mostly made out of hydrogen, WASP-39 b is probably not habitable. But JWST’s latest observations emphasise how it can be used to find potential evidence of life on distant planets.

First published on: 28-11-2022 at 13:10 IST
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