Just a Short Cosmic Hop

Monday, April 21, 2025

Just a Short Cosmic Hop

In a headline I first found thanks to Drudge Report, a story from Reuters describes new evidence of a fairly close planet that bears the biochemical signatures of living organisms.

The planet, doing business under the catchy name K2-18b, orbits a star around 120 lightyears away and is within the “habitable” zone in which liquid water should potentially exist. Its atmosphere was first analyzed in 2023 and found to contain dimethyl sulfide (DMS), which is a known byproduct of oceanic bacterial life. The analysis was repeated recently, and this second study found additional signs of dimethyl disulfide (DMDS), providing support that the initial observations were on the right track.

Here’s an excerpt from the Space.com report on the news:

"This is an independent line of evidence, using a different instrument than we did before and a different wavelength range of light, where there is no overlap with the previous observations," Nikku Madhusudhan, a professor at Cambridge University's Institute of Astronomy, who led both K2-18b studies, said in a statement today. "The signal came through strong and clear."

Based on its size and other characteristics, astronomers suspect that K2-18b may be a "Hycean" world — a class of exoplanet proposed in 2021 that has a huge liquid-water ocean and a hydrogen-rich atmosphere. ("Hycean" is a portmanteau of "hydrogen" and "ocean.")

The article goes on to point out that the trace chemicals would appear to support hypotheses about Hycean worlds in the habitable zone. The planet is estimated to be roughly nine times as massive as Earth at around 2.5 times Earth’s radius. Skeptics also receive the last word in the piece.

The recent discovery was thanks to NASA’s James Webb Space Telescope. The planet’s Wikipedia page is here.

Wouldn’t it be nifty if we were to launch a probe on a multi-century round-trip flight to K2-18b to bring us back some close-up polaroids? I’d call that nifty. Maybe even a sign that we were hopeful about our long-ahead future selves.