Scientists are rethinking how to detect alien life by focusing on planets vastly different from Earth. Instead of searching for familiar biosignatures like oxygen, they’re investigating methyl halides

These gases — composed of carbon, hydrogen, and a halogen, like chlorine — are mostly made by bacteria, algae, fungi, and plants. The chemicals are particularly intriguing as a potential sign of life because they can be detected in infrared light, which is Webb's viewing specialty.

The study builds on previous research investigating different biosignature gases, including dimethyl sulfide, another potential sign of life. However, methyl halides appear particularly promising because of their strong absorption features in infrared light as well as their potential for high accumulation in a hydrogen-dominated atmosphere.