Mars was once wet, many scientists say. Now it's dry. For the first time, a geological map of the entire planet is revealing the history of its dessication.

Watch animation of NASA's proposed plan to crash a probe into the moon in search of lunar water, and hear a NASA scientist describe the probe's historic suicide mission.

NASA's first moon landing in more than 30 years will end with a bang, when a space probe launched in 2008 crashes into the moon's south pole to stir up signs of water ice.

The remote-controlled airplane-glider hybrid can find and ride air currents and may be used for flights on distant planets or spy missions on Earth.

A disk of debris circling a pulsar 13,000 light-years from Earth sheds new light on how and where planets can form.

Billions of years ago a giant space rock slammed into Mercury, leaving the planet less than half its previous size, according to new computer simulations.

X-ray images of comet Tempel 1's collision with the Deep Impact space probe last year show that the comet released about 250,000 tons (226,800 metric tons) of water.

Roughly the size of football fields, the moonlets may hold the secret to where the rings came from.

The coolest view of today's solar eclipse might have been from hundreds of miles above the Earth, as shown in a photo taken this morning from the International Space Station.

Astronomers have discovered a "cool" brown dwarf circling a small star about 12.7 light years from the sun.

Scientists studying Martian formations that suggest water recently ran on the red planet might have to curb their enthusiasm—reexamination of lunar photos from 1969 shows similar features on the moon.

The oldest light ever detected appears to confirm the theory that the universe went from marble size to astronomical proportions in a split second.

Looking for signs of life in outer space? Here's one that scientists really weren't expecting: an entire nebula shaped like a DNA double helix.

Surprising scientists, NASA's Stardust spacecraft has apparently found minerals formed near the sun around a comet from the fringes of our solar system.

Scientists have discovered a new planet they call a "super-Earth" in a solar system 9,000 light-years away.