Phosphine is a colorless, flammable, toxic gas that smells like rotting fish. Humans manufacture it to use in pest control and the production of computer chips. But it’s also a waste product from a certain kind of “abiotic” microbe that lives in oxygen-free environments. Its presence is a potential sign that there’s something alive.
The gas with the chemical name PH3 has been at the center of a passionate debate among scientists concerned with, well, life: what it is, what it needs to survive, and where it could be located elsewhere in the universe.
On one side are are scientists and their supporters who, a year ago, claimed they had detected signs of phosphine in the practically unlivable atmosphere of Venus—the second planet from the sun best known for its boiling, 800-degree-Fahrenheit surface and thick clouds made not of water, but acid. Whether intentionally or not, these researchers set off the alarms that perhaps we have discovered signs of extraterrestrial life on another world.