The first alien ID chart

How would Earth look (observed by an alien astronomer) seen through geological time, from its birth to today? And how good do our instruments need to be to not miss signatures of life through Earth’s evolution until now?  We generate the “spectral fingerprints” of Earth through geological times using fossil records as proxy for evolutionary stages of an exoEarths. An alien ID chart…

Paper: Kaltenegger, L et al., Spectral Evolution of an Earth-like Planet, ApJ 658, 598, 2007 Institute for Pale Blue Dots

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