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Astronomy

Detecting atmospheric biosignatures in exoplanet transmission spectra

Quick fact

When a planet passes in front of its star, the starlight skimming through the planet's atmosphere is partially absorbed, imprinting the atmosphere's 'fingerprint' on the light. This allows astronomers to detect gases like oxygen and methane from tens of light-years away.

Why this is interesting

Imagine trying to figure out what's in a distant planet's air by watching a tiny dip in a star's brightness. How can a few missing colors of light reveal secrets about alien life?