The 365 Days of Astronomy Astronomy Cast Ep. 754: K2-18b
May 5, 2025
Discover the exciting find of biosignatures on exoplanet K2-18b, raising questions about the possibility of extraterrestrial life. Delve into the unique characteristics of this sub-Neptune, including its potential for liquid water. Explore the challenges scientists face in interpreting atmospheric data from the Hubble and James Webb Space Telescopes. Balance skepticism and excitement as the podcast navigates the scientific discourse and community support fueling this groundbreaking research.
AI Snips
Chapters
Transcript
Episode notes
K2-18b's Habitable Zone Orbit
- K2-18b orbits a red dwarf star with a 32.9-day period inside its habitable zone, receiving Earth-like energy levels.
- Its size and mass suggest it is a sub-Neptune or super-Earth with a thick atmosphere and potential for liquid surface water.
Initial Water Detection Ambiguity
- Hubble Space Telescope detected water absorption features in K2-18b's atmosphere but with low significance and ambiguity.
- Spectra were low resolution and could be explained by molecules like methane as well.
Webb's Spectral Clarity Leap
- James Webb Telescope greatly improved spectral data, confirming methane and carbon dioxide in K2-18b's atmosphere.
- The precision jump from Hubble to Webb allows more definitive assessment of atmospheric chemicals.