James Webb Telescope finds evidence of carbon dioxide on a distant exoplanet for the first time

Artist's impression of the exoplanet WASP-39
Artist's impression of the exoplanet WASP-39 Copyright NASA, ESA, CSA, Joseph Olmsted
By Luke Hurst
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Scientists working on the project said they are now "crossing an important threshold in exoplanet sciences".


NASA’s new space telescope has been providing us with awe-inspiring images of the cosmos since it went into operation this summer.

The James Webb Space Telescope has already unveiled parts of the universe that had previously never been observed, as well as showcasing stunning images of the biggest planet in our solar system, Jupiter.

But the telescope’s capabilities don’t end there.

Scientists have found the first clear evidence of carbon dioxide in the atmosphere of an exoplanet, a breakthrough discovery that could open the door to similar observations on planets more hospitable to life.

That’s a planet that is outside of our solar system - in this case, a gas giant orbiting a star similar to our Sun, some 700 lightyears away. 

"As soon as the data appeared on my screen, the whopping carbon dioxide feature grabbed me," said Zafar Rustamkulov, a graduate student at Johns Hopkins University and member of the JWST Transiting Exoplanet Community Early Release Science team, which undertook this investigation.

"It was a special moment, crossing an important threshold in exoplanet sciences".

James Webb's abilities

The findings, accepted for publication in the journal Nature, show that the telescope may therefore be able to detect and measure CO2 in the atmospheres of smaller rocky planets.

The planet, WASP-39 b, is a gas giant a little larger than Jupiter. It was first discovered in 2011, from ground-based observations of dimming of light from its host star as the planet passed in front of it.

Previous studies have revealed the presence of water vapour, sodium, and potassium in the planet’s atmosphere, but only James Webb’s superior infrared sensitivity was able to confirm beyond a doubt the presence of carbon dioxide.

"Detecting such a clear signal of carbon dioxide on WASP-39 b bodes well for the detection of atmospheres on smaller, terrestrial-sized planets," said Natalie Batalha of the University of California at Santa Cruz, who leads the team.

NASA says the results show the telescope’s ability to gather insights into the composition, formation, and evolution of planets across the galaxy.

"Carbon dioxide molecules are sensitive tracers of the story of planet formation," said Mike Line of Arizona State University, another member of this research team.

"By measuring this carbon dioxide feature, we can determine how much solid versus how much gaseous material was used to form this gas giant planet. In the coming decade, JWST will make this measurement for a variety of planets, providing insight into the details of how planets form and the uniqueness of our own solar system".

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