How and Why Earth Went From Purple to Green - Twice

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.

Life on Early Earth
Photosynthesis on Early Earth
Contrasting Colors of Photopigments
Purple Earth Hypothesis
Phototrophy vs Photosynthesis
Purple vs Green Phototrophs
From Purple To Green Earth
Evidence for Purple Earth
Rise of Photosynthesis
Second Purple Earth?
Transition to Green Earth
Using Pigments to Find Aliens?