Sep 4, 2022 - Science

JWST detects carbon dioxide in alien planet's atmosphere for 1st time

Artist's illustration of a planet around its star.

Artist's illustration of WASP-39 b. Image: NASA, ESA, CSA, and J. Olmsted (STScI)

The James Webb Space Telescope has detected carbon dioxide in the atmosphere of a distant planet circling a Sun-like star for the first time.

Why it matters: The JWST is designed to investigate and help scientists understand the compositions of exoplanet atmospheres in the hopes of eventually figuring out exactly what might make a world habitable.

  • While this detection was made in the atmosphere of a gas giant that likely isn't hospitable to life, it could help scientists figure out what a signal from carbon dioxide might look like for a potentially habitable world.

What's happening: The planet called WASP-39 b — which has close to the same mass as Saturn but is wider in diameter than Jupiter — is located about 700 light-years away.

  • The JWST caught sight of the planet as it passed in front of its star, backlighting its puffy atmosphere and allowing the telescope to parse out what it was made of.
  • During a transit like this, the light from the star is partially obscured by the planet and starlight is filtered through the atmosphere, which lets scientists get a spectrum of colors that represent various molecules that compose the atmosphere.
  • "Detecting such a clear signal of carbon dioxide on WASP-39 b bodes well for the detection of atmospheres on smaller, terrestrial-sized planets," Natalie Batalha of the University of California at Santa Cruz who led the team behind the discovery said in a statement.

Plus: "Carbon dioxide molecules are sensitive tracers of the story of planet formation," Mike Line, a team member from Arizona State University, said.

  • "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," Line added.
  • "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."

Go deeper: How the James Webb Space Telescope's images are made

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