Aliens could be purple and not green, a new study claims. Astronomers are expanding the search for extraterrestrial life beyond the conventional green pigments. Recent research by scientists from the Carl Sagan Institute and Cornell University has discovered that purple bacteria can thrive under a variety of diverse conditions Lead study author Ligia Fonseca Coelho said: "They already thrive here in certain niches. Just imagine if they were not competing with green plants, algae and bacteria: A red sun could give them the most favorable conditions for photosynthesis.” This includes planets orbiting dim red stars, suggesting that alien life forms might actually be purple.