Podcaster: Beth Johnson, Franck Marchis, and Simon Steel (alternate hosts); Guest: Dr. Nikku Madhusudhan

Title: SETI Live: Atmospheric Results from JWST: Carbon Dioxide, Methane, and More

Organization: SETI Institute

Link: ; Preprint of the paper:


Exoplanet discoveries have been piling up faster and faster over the last decade, limiting announcements of new discoveries to the strange, unusual, and unexpected. One unexpected type of planet is the possible Hycean world — hot, water-covered worlds with hydrogen atmospheres larger than Earth but smaller than Neptune with sizable habitable zones. 

With the addition of JWST’s capabilities, previously discovered exoplanets are now being analyzed for their atmospheric composition, and the results are intriguing. In a new paper accepted for The Astrophysical Journal Letters, the atmosphere of an exoplanet known as K2-18 b was found to contain carbon dioxide and methane, adding the world to the list of possible Hycean planets. Additionally, a molecule called dimethyl sulfide, which on Earth is only produced by life, was possibly detected.

Join communications specialist Beth Johnson as she speaks with lead author Dr. Nikku Madhusudhan, an astronomer at the University of Cambridge, in a SETI Live at a special time. (Recorded live on 21 September 2023.)

Bio: Beth Johnson is a communications specialist and social media manager with a degree in physics and master’s work in planetary science. She specializes in meteor showers, icy moons, and anything with volcanoes.

Franck Marchis is a senior planetary astronomer and chair of the exoplanet group at the Carl Sagan Center of the SETI Institute and Chief Scientific Officer and Founder at Unistellar. He has dedicated his work to the study of our solar system, specifically the search for asteroids with moons, using mainly ground-based telescopes equipped with adaptive optics.

Simon Steel is Deputy Director of the Carl Sagan Center for Research at the SETI Institute. As an observational astrophysicist, he specialized in optical spectrophotometry, with an interest in the star formation histories of galaxies.

Dr. Nikku Madhusudhan, an astronomer at the University of Cambridge, in a SETI Live at a special time.

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