Key science questions

Sagan et al. (1993) analyzed a spectrum of the Earth taken by the Galileo probe, searching for signatures of life and concluded that the large amount of O2 and the simultaneous presence of CH4 traces are strongly suggestive of biology. To characterize a planet's atmosphere and its potential habitability, we look for absorption features in the emergent and transmission spectrum of the planet. The spectrum of the planet can contain signatures of atmospheric species, what creates its spectral (...)