Scientists believe Earth was once purple, not green. Around 2 billion years ago, early life forms used a pigment called retinal to capture sunlight. This pigment absorbs green light, unlike modern plants that use chlorophyll to absorb red and blue light. Retinal-powered life likely thrived before chlorophyll appeared. Around 2.4 billion years ago, the Great Oxygenation Event caused oxygen to rise in Earth's atmosphere. This change is linked to cyanobacteria that perform photosynthesis using chlorophyll. But photosynthetic life existed long before, which puzzles scientists about the slow oxygen increase. Professor Shiladitya DasSarma from the University of Maryland and Dr Edward Schwieterman from the University of California explain that both pigments evolved to absorb different sunlight wavelengths. "Retinal-based phototrophic metabolisms are still prevalent throughout the world, especially in the oceans, and represent one of the most important bioenergetic processes on Earth," says DasSarma. Early Earth’s purple color came from retinal-containing microbes like halobacteria, which reflect red and blue light and appear purple. Over time, chlorophyll evolved, enabling plants to use sunlight more efficiently and turn Earth green. Retinal-based life forms remain but are no longer dominant. This new research shifts our view of Earth’s early life and its colors, revealing a vibrant, purple start before the green planet we know today.