While the James Webb Space Telescope observed the atmosphere of an alien world 120 light-years away, it picked up hints of a substance only made by living things — at least, that is, on Earth.
This molecule, known as dimethyl sulfide, is primarily produced by phytoplankton, microscopic plant-like organisms in salty seas as well as freshwater.
The detection by Webb, a powerful infrared telescope in space run by NASA and the European and Canadian space agencies, is part of a new investigation into K2-18 b, an exoplanet almost nine times Earth's mass in the constellation Leo. The study also found an abundance of carbon-bearing molecules, such as methane and carbon dioxide. This discovery bolsters previous work suggesting the distant world has a hydrogen-rich atmosphere hanging over an ocean.
"This (dimethyl sulfide) molecule is unique to life on Earth: There is no other way this molecule is produced on Earth," said astronomer Nikku Madhusudhan in a University of Cambridge video. "So it has been predicted to be a very good biosignature in exoplanets and habitable exoplanets, including Hycean worlds."