Earth was once purple, not green! Early microbes used retinal, not chlorophyll, for photosynthesis, reflecting violet hues. This ancient color shift hints at alien life.

Some scientists propose that Earth was once covered in shades of purple instead of green. The idea suggests early life forms used a different molecule for photosynthesis than today’s chlorophyll.

This stunning photo was taken on January 29, 2025, from 265 miles (425 km) above the Pacific Ocean. Pettit, a seasoned ...

According to co-author Lisa Kaltenegger, purple bacteria's ability ... This marked a pivotal moment in Earth's history, as these tiny blue-green algae released oxygen as a byproduct of their ...