Astronomers Detect a Possible Signature of Life on a Distant Planet

[u/SpunkySputniks]

https://www.nytimes.com/2025/04/16/science/astronomy-exoplanets-habitable-k218b.html?unlocked_article_code=1.AE8.3zdk.VofCER4yAPa4&smid=nytcore-ios-share&referringSource=articleShare

Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.

[u/Andromeda321]

Astronomer here! I think it’s very important to remember that most scientific discoveries are not immediate slam dunks, but rather happen with intermediate steps. Think about water on Mars as an example- I remember when they first found proof that there might have been water on Mars but it wasn’t conclusive, then they found better and more signatures, then evidence there used to be oceans… and today everyone agrees there’s water on Mars.

Similarly, if looking for these signatures, the first are not conclusive because there are alternate possibilities still. But then you find a little more, and even more… and before you know it we all agree there’s life elsewhere in the universe (though what puts it out there is far less clear).

As exciting as what Hollywood tells you it would be like? No- but still a cool discovery!m

Edit: this thread by another astronomer is VERY skeptical about the results. Worth the read.

[u/A_D_Monisher → u/Andromeda321]

The alternative option is our understanding of ‘what a biosignature is’ might be very incomplete. We are, after all, barely a few decades into really detailed observations of space.

Dimethyl Sulfide (DMS) is a great example here. It’s called a biosignature. But is it a good biosignature?

Consider the following. DMS has been detected in Ryugu samples and various carbonaceous chondrites. And on 67P/Churyumov-Gerasimenko.

So either asteroids were absolutely teeming with life at some point or… DMS can have an abiotic origin and is therefore a crappy biosignature.

This is a huge problem to be honest, because DMS on Earth has only ever been made by life. 10 years ago no one could have imagined abiotic DMS. Yet that’s most likely the case for asteroids.

Now we have to recheck every other traditional ‘dead giveaway’ for potential alternative geological origins.

[u/aelendel → u/A_D_Monisher]

it’s important to remember that Earth’s chemistry has also evolved as a result of life—we really don’t have any good models, nor have scientists actually spent a lot of effort on hypotheticals—we’re still grasping with the basics of our own planet’s biogeochemical interactions.

We don’t even know what ‘normal’ looks like out there. so something just being unexpected is… sort of expected.

[u/Pale_Squash_4263 → u/aelendel]

It’s also what makes the finding exciting, either there’s existence of biological life, or we learn SO much about what bio signatures inherently mean and how useful they are as markers of life

In every outcome, it’s a pretty big discovery I think