Millions of people around the world will pause, at least for a moment, to mark Earth Day. The annual event is Wednesday.

Scientists reveal how Earth flipped into an ice age 350 million years ago, uncovering a major shift in the planet’s ancient ...

Imagine Earth at a time when it was almost unrecognizable—a landscape that was barren and with barely breathable air. That is what Earth looked like about 1.75 billion years ago. But scientists now ...