New methane readings from a space probe raise the possibility that microbial life could exist on Mars. Some scientists, though, remain skeptical.

How did the building blocks of life arise on Earth? A new study says a volcanic gas may have been the key.

When Mount St. Helens erupted in 1980, people hundreds of miles away heard the roar. The blast turned day to night, leveled miles of forest, and claimed 57 lives.

Scientists say they have found a small, earlier cousin of Tyrannosaurus rex that had at least a partial coat of feathers. Includes image gallery.

Like the woolly mammoth, a giant, prehistoric deer survived the last ice age, a new study shows. So what caused the Irish elk's eventual extinction?

Wild chimpanzees have been filmed using tools in combination to extract termites from mounds—further evidence that tool use is not unique to humans.

Fall foliage delights leaf-peeping tourists, but how does the change in color benefit trees? As scientists explain, there is a reason for the season.

Bees, via pollination, are responsible for 15 to 30 percent of the U.S. food supply. But in the last 50 years the domesticated honeybee population has halved, scientists say.

SpaceShipOne, the world's first privately built manned spacecraft, completed its third round-trip journey to space today, laying claim to the ten-million-dollar (U.S.) Ansari X Prize.

While leaves tumble from trees this fall, another natural wonder is soaring overhead. Hawks in North and South America are taking to the air as part of a seasonal migration.

Mount St. Helens blew a cloud of steam and gray ash into the skies over Washington State earlier today. Observers reported the eruption lasted 20 minutes.

SpaceShipOne, the first privately built, manned vehicle to reach space, roared to space and back again this morning from a launch site in California's Mojave desert.

Pick your vehicle—stock car, motorcycle, pickup truck, riding lawn mower—and competitors in the United States race them. So, too, the solar-powered car.

Earth's magnetic field has flipped many times over the last billion years. But only recently have scientists developed computer models to reveal how these reversals occur.

Tumbling through space like a fumbled football, a peanut-shaped asteroid named 4179 Toutatis is expected to pass within a million miles (1.6 million kilometers) of Earth today.