Redefining the Photosynthetic Habitable Zone

Astronomers, led by University of Georgia astrophysicist Cassandra Hall, propose rethinking the habitable zone to include factors beyond water, focusing on starlight intensity, surface temperature, atmospheric density, and energy expenditure for survival. By estimating a photosynthetic habitable zone closer to a planet's star than the traditional habitable zone for water, five rocky exoplanets including Kepler-452b and Kepler-62f are identified as promising candidates likely to support plant life. The search for signs of life on these distant worlds involves detecting specific chemical signals such as those indicating disequilibrium, potentially expanding the understanding of habitable zones beyond Earth-centric notions.