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 ...

In that moment, all of humanity was captured in a ghostly fragment of a pixel swimming through an unrelenting sea of darkness — a "Pale Blue Dot" lost in a void. Carl Sagan — the astronomer ...