How Scientists Detect Air on Planets Dozens of Light-Years Away
How can we tell whether a rocky planet dozens of light-years away has an atmosphere? For a few hours, as the planet crosses in front of its star, starlight grazes its air and comes out with a few colors missing. SORABUMI explains how transit spectroscopy reads that 'color fingerprint,' and why the clue shrinks to the thickness of an apple peel once you're talking about an Earth-sized world.
