Before plants ruled, Earth may have glowed violet. The first life forms used retinal instead of chlorophyll, absorbing green light and reflecting red and blue—turning the planet an eerie purple.

For most of human history, Earth has been known as the “Pale Blue Dot,” a term popularized by astronomer Carl Sagan when referring to the iconic 1990 image taken by Voyager 1. But for billions of ...

Although the Earth’s been decidedly blue for 600 million years, rising populations of phytoplankton caused by rising ...

Earth's oceans may have been green for billions of years until the first photosynthetic organisms flooded our atmosphere with oxygen.

For a long stretch of Earth’s history, our planet might have looked green from a distance, instead of the pale blue dot we know today. Earth’s green period, which lasted from around 3 billion ...

Enjoy Earth Day with a glass of refreshing celery ... With its tender stem and vibrant green color, this versatile veggie is a must-try. Get the Roasted Frozen Asparagus recipe.