To spot the tint of Earth, alien astronomers from Andromeda might measure light shimmering off the surface of a planet, as sunlight reflected from our planet’s vegetation reaches their telescopes. Conversely, astronomers here can see pigmentation on exoplanets and determine their makeup by looking at their color. “Our results show the amazing diversity of life that one can detect remotely on exoplanets,” said Hegde. Widespread plant life is only about 500 million years old on Earth. So a younger Earth or a different kind of Earth (just a bit hotter or colder or more acid) might look very different, placing colorful worlds into our night sky - too faint to spot for a little while longer until the next big telescopes come online. “On Earth these are just niche environments, but on other worlds, these life forms might just have the right make to dominate, and now we have a database to know how we could spot that,” said Kaltenegger.