Searching for Life Across Worlds: Habitats in the Solar System and Biosignatures on Exoplanets

To the point

Life detection hinges on two routes, exploring solar-system bodies for habitable conditions and searching distant exoplanets for atmospheric biosignatures, because habitability depends on energy sources and chemical exchange between oceans and rocks, and even planets in the habitable zone may not reveal life or be easy to diagnose, a caution Carl Sagan voiced when he called life the hypothesis of last resort.