Meet asteroid 1999 RQ36, a chunk of rock and dust about 1,900 feet in diameter that could tell us how the solar system was born, and perhaps, shed light on how life began. It also might hit us someday.

By precisely tracking NASA's Cassini spacecraft on its low swoops over Saturn's moon Titan, scientists have determined the distribution of materials in the moon's interior. The subtle gravitational tugs they measured suggest the interior has been too cold and sluggish to split completely into separate layers of ice and rock.

Fixed to a tripod, a camera can record graceful trails

What's happening on the surface of Saturn's moon Helene?

The two galaxies on the far left were unknown until 1968.

What's that bright object in the sky?

Is it art?

Pillar at Sunset

Who are these masked men?

Take a bunch of fast-moving electrons, place them in orbit and then hit them with the shock waves from a solar storm. What do you get? Killer electrons. That's the shocking recipe revealed by ESA's Cluster mission.

By precisely tracking NASA's Cassini spacecraft on its low swoops over Saturn's moon Titan, scientists have determined the distribution of materials in the moon's interior. The subtle gravitational tugs they measured suggest the interior has been too cold and sluggish to split completely into separate layers of ice and rock.

Three of Saturn's small moons straddle the rings in this image. From left to right are Pandora, Prometheus and, near the top right, Epimetheus. Pandora and Prometheus are closest to Cassini. Epimetheus is on the far side of the rings. This view looks toward the northern, sunlit side of the rings from just above the ringplane. The shadow of Saturn is cast upon the rings, darkening the middle of the image from left to right.

Scientists studying Titan have found analogies to a type of spectacular terrain on Earth known as karst topography.

A day after a targeted flyby of the moon Rhea, the Cassini spacecraft made its closest approach of the mission to Helene at about 1,800 kilometers (1,131 miles). The small moon is referred to as a trojan moon because it is gravitationally tied to the much larger moon Dione.

On March 2, 2010, Cassini swooped down to within about 100 kilometers of Rhea to ?sniff? the moon. Particle and fields instruments will use the data collected to try to determine what is coming off Rhea.

By precisely tracking NASA's Cassini spacecraft on its low swoops over Saturn's moon Titan, scientists have determined the distribution of materials in the moon's interior.

NASA's venerable Mars rover Spirit is starting a second career as an explorer of the Martian core--but first it must survive the deadly Martian winter.

NASA's Solar Dynamics Observatory amazed onlookers last week when it flew past a sundog and destroyed it. Must-see videos of the event captured shock waves from the rocket billowing through the sundog, eliciting cries of delight and amazement from the crowd below.

Imagine holding the entire sun in the palm of your hand. Now you can. A new iPhone app developed by NASA-supported programmers delivers a live global view of the sun directly to your cell phone.

Terrestrial gamma-ray flashes (TGFs) surge through thunderstorms at about the same altitude where commercial airliners fly. Do these blasts of gamma-radiation pose a hazard to air travelers?