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.

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

Scientists have discovered that alien existence could be hiding in gases on distant planets. New research suggests extraterrestrial beings might exist in gases called methyl halides on faraway worlds.