Scientists detect possible signature of life on a distant planet

The search for life beyond Earth has led scientists to explore many suggestive mysteries, from plumes of methane on Mars to clouds of phosphine gas on Venus.

- CARL ZIMMER

But as far as we can tell, Earth's inhabitants remain alone in the cosmos.

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.