Now a team of researchers is offering what it contends is the strongest indication yet of extraterrestrial life, not in our solar system but on a massive planet, known as K2-18b, that orbits a star 120 light-years from Earth. A repeated analysis of the exoplanet’s atmosphere suggests an abundance of a molecule that on Earth has only one known source: living organisms such as marine algae. “It is in no one’s interest to claim prematurely that we have detected life,” said Nikku Madhusudhan, an astronomer at the University of Cambridge and an author of the new study, at a news conference on Tuesday. Still, he said, the best explanation for his group’s observations is that K2-18b is covered with a warm ocean, brimming with life. “This is a revolutionary moment,” Dr. Madhusudhan said. “It’s the first time humanity has seen potential biosignatures on a habitable planet.”

Thanks to NASA's powerful James Webb Space Telescope (JWST), astronomers have found the best evidence yet of life on another world outside our solar system. For years, the exoplanet K2-18b has been a top contender with promising signs of life. New research led by the University of Cambridge has found evidence of chemicals within K2-18b's atmosphere that on Earth are produced by marine life, like algae and phytoplankton. K2-18b orbits its parent star within the constellation Leo, 124 light years away, and is more than 2.5 times larger than Earth. This world is known as a "Hycean" planet because it could contain an ocean underworld teeming with life and a hydrogen-rich atmosphere.

Astronomers have discovered a major sign of life — and “the first hints… of an alien world” on a distant planet orbiting outside the solar system, according to a new report. The scientists believe the exoplanet, K2-18b, is a “Hycean planet” — meaning it’s home to an abundance of a life-signifying molecules including one that is only produced on Earth by living organisms such as marine algae, according to a new report. K2-18b — which is eight times the size of Earth and 124 light-years away — shows signs of the unique molecule dimethyl sulfide, according to a new study published in the Astrophysical Journal on Wednesday.