"Another biomarker might be a planet's colour. Chlorophyll, the chemical that controls photosynthesis, is green for a reason. It is tuned to the spectrum of the sun in order to absorb sunlight in the most efficient way possible. The reflected green is the light it rejects. That calculation could be made for any star, and the best colour for a chlorophyll equivalent worked out. Perhaps if the exoplanet under investigation were orbiting a dwarf star, the little green men—or, at least the vegetation they eat—might turn out to be orange."
That would be a sight, a planet with a completely different set of colors from what we're used to here. Cool.