How Do We Know What We’re Seeing on K2-18b? | Dr. Luis Welbanks and Dr. Matt Nixon

As a listener of Event Horizon, you get a special 20% off discount. Head over to The Economist's website at https://www.economist.com/EventHorizon to get started. Exploring the evolving field of exoplanet atmospheres with Dr. Luis Welbanks and Dr. Matt Nixon. With an update on exoplanet K2-18b atmosphere characterization. Welbanks and Nixon examine the complexities and challenges outlined in their paper, "The Challenges of Detecting Gases in Exoplanet Atmospheres" (Welbanks et al., 2025), addressing crucial issues in accurately identifying atmospheric components in exoplanets using the James Webb Space Telescope. Exploring how JWST is transforming our understanding of distant worlds. Reference: Welbanks, L., Nixon, M. C., McGill, P., Tilke, L. J., Wiser, L. S., Rotman, Y., Mukherjee, S., Feinstein, A., Line, M. R., Seager, S., Beatty, T. G., Seligman, D. Z., Parmentier, V., & Sing, D. (2025). The Challenges of Detecting Gases in Exoplanet Atmospheres. arXiv:2504.21788. https://doi.org/10.48550/arXiv.2504.21788 0:00 Introduction and Welcome 3:03 Exploring Exoplanet Atmospheres 6:04 Limitations and Challenges in Observing Atmospheres 9:04 Confidence in Atmospheric Detection Results 12:06 Confirming Chemical Species in Atmospheres 15:07 Accounting for Stellar Effects in Observations 18:07 Observing Variability in Exoplanet Atmospheres 21:08 Distinguishing Water Vapor from Methane in K2-18b 24:10 The Alien Nature of Mini-Neptunes 27:10 Imagining Exotic Chemical Processes 30:11 Atmosphere Retention in Mini-Neptunes 33:12 Using JWST to Study Young Planetary Systems 36:12 Observational Capabilities of JWST and Future Telescopes 39:12 Hycean World Hypothesis 42:14 Understanding Atmospheric Chemistry Models 45:16 Historical Context and Early Exoplanet Discoveries YouTube Membership: https://www.youtube.com/channel/UCz3qvETKooktNgCvvheuQDw/join Podcast: https://anchor.fm/john-michael-godier/subscribe Apple: https://apple.co/3CS7rjT More JMG https://www.youtube.com/c/JohnMichaelGodier Want to support the channel? Patreon: https://www.patreon.com/EventHorizonShow Follow us at other places! @JMGEventHorizon Music: https://stellardrone.bandcamp.com/ https://migueljohnson.bandcamp.com/ https://leerosevere.bandcamp.com/ https://aeriumambient.bandcamp.com/ FOOTAGE: NASA ESA/Hubble ESO - M.Kornmesser ESO - L.Calcada ESO - Jose Francisco Salgado (josefrancisco.org) NAOJ University of Warwick Goddard Visualization Studio Langley Research Center Pixabay