Astronomers have made a detection suggesting biosignatures, or signs of biological activity, on an exoplanet located 124 light-years away. But experts are skeptical.

Other scientists urged caution. A "molecule glimpsed in the air of a planet 729 trillion miles away is a thin reed upon which to rest what would be the historic discovery of alien life," The Washington Post said.

Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.