Explore the fascinating hypothesis of Earth's purple past in this 21-minute video. Delve into the evolution of photosynthetic organisms and their impact on our planet's appearance from space. Learn about the two potential "Purple Earth Events" in Earth's history, examining the evidence behind these theories and their implications. Discover the differences between phototrophy and photosynthesis, and how various pigments used by ancient microorganisms may have influenced Earth's color. Investigate the transition from purple to green Earth, the rise of cyanobacteria, and the potential for a second purple period during the "boring billion." Conclude by considering how understanding Earth's color changes could aid in the search for extraterrestrial life.