Astronomers are expanding the search for extraterrestrial life beyond the conventional green pigments. Recent research has discovered that purple bacteria can thrive under a variety of diverse conditions. "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," explained lead study author Lígia Fonseca Coelho from the Carl Sagan Institute in New York. This includes planets orbiting dim red stars, suggesting that alien life forms might actually be purple. These microbes, which utilize a purple-pigmented molecule called retinal for photosynthesis, could leave detectable biosignatures. Led by scientists from the Carl Sagan Institute and Cornell University, the study offers a new avenue for identifying life beyond Earth.