the.com/biosignatures
the cosmic fingerprints life leaves even when it forgets to say hello.
means a biosignature is any substance, pattern, or chemical imbalance in a planet's atmosphere or rocks that suggests something alive made it.
from the term grew out of astrobiology in the late 20th century, as scientists sought a rigorous word for what earlier eras just called signs of life, especially once space telescopes made distant atmospheres readable.
oxygen tellfree oxygen shouldn't exist without something replenishing it
false alarm riskphosphine on venus turned out ambiguous, not proof
earliest kindstromatolites are 3.5 billion year old bacterial signatures
telescope huntjwst now scans exoplanet atmospheres for these clues