An accidental skid by the Mars rover Spirit turned up what experts say is proof that the red planet was once quite wet.

A comet exploded over North America about 13,000 years ago, causing massive mammal die-offs and the demise of one of the earliest American cultures, according to a controversial new theory.

Software under development at NASA could adjust airplane controls to help pilots keep their craft in control even when faced with catastrophic failures.

A Neptune-size planet likely covered in hot—but solid—water has been discovered in a snug orbit around a nearby star, a team of astronomers announced today.

More than 700 new species of bizarre sea animals have been found in the deep waters off Antarctica, researchers say.

Three collisions between the Milky Way and Andromeda galaxies are likely to leave Earth in a remote, lonely region of space, a new study suggests.

Some common U.S. birds saw declines of up to 45 percent from the West Nile virus, a new study shows—suggesting even the most familiar birds are surprisingly vulnerable.

New theories about what's creating geysers of water on Saturn moon's Enceladus may put hopes for life there on ice.

Images from the Hubble Space Telescope have provided what astronomers say is the strongest evidence yet for the existence of dark matter.

Mites provide poison frogs with most of their toxic sting, at least in the lowlands of Panama and Costa Rica, a new study shows.

A bizarre area in Canada with weaker-than-expected gravity is caused partially by land still recovering from the heavy burden of Ice Age glaciers.

Astronomers believe they may have found a significant portion of the universe's "missing" dark matter hidden in unusual galaxies formed by giant collisions.

Bat wings work in a completely different way than those of birds—and may pave the way for versatile new search-and-rescue and reconnaissance aircraft.

Our solar system flies through space faster than a speeding bullet—and in the same shape as one, according to data from the two Voyager spacecraft.

A tiny opossum is revealing big potential for understanding human evolution, treating cancer, and learning how to repair damaged spinal cords.