happened to collide with the Earth. The best-known episode is that in which the dinosaurs died 65 million years ago, but there have been many other catastrophic impacts both before then, and since.

Humans have long imagined life on Mars, but what if the red planet actually delivered life to Earth in the first place?

On August 23, 1966, NASA’s Lunar Orbiter 1 captured the very first photograph of Earth from the vicinity of the Moon, showing our planet as a delicate crescent rising above the lunar horizon. While ...

Since the beginning of Earth's history, tiny particles of rock and metal from space have been hitting our planet. On clear nights, we can even see their traces as shooting stars. Trapped in layers of ...

Continental clues: Modern continental rocks carry chemical signatures from the very start of our planet’s history, challenging current theories about plate tectonics. Researchers have made a new ...

Earth's continental configurations have changed dramatically over its billions of years' history, transforming not only their positions across the planet, but also their topography as expansion and ...

CU Boulder professors explain Earth Day’s history, impact, what it’s become and if it’s still relevant If you were at the University of Colorado Boulder in April 1970, you were likely aware―very aware ...

He works in mysterious ways.

On Sept. 22, the autumnal equinox, which signals the start of fall in the Northern Hemisphere, finally brings an end to our long, hot summer on Monday at 2:19 p.m. EDT. This happens at a precise ...