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?

The Solar Dynamics Observatory (SDO), slated for liftoff on Feb. 9th, will make IMAX-quality movies of solar explosions, peer beneath the stellar surface to see the sun's inner dynamo, and--researchers hope--unravel the mysteries of solar variability.

NASA's Hubble Space Telescope has observed a mysterious X-shaped debris pattern and trailing streamers of dust that suggest a head-on collision between two asteroids.

There's a mystery in the skies of Earth: Something is producing bright flashes of gamma radiation in the upper atmosphere of our own planet. A new NASA-NSF mission called Firefly is going to investigate.

This week Earth and Mars are having a close encounter. On Jan. 27th, the Red Planet will be only 99 million kilometers away and look bigger through a telescope than at any time between 2008 and 2014.

NASA announced today that Mars rover Spirit cannot be freed from its Martian sandtrap. Now the rover will begin a second career as a stationary science platform.

Evidence is mounting that a strong magnetic field lurks just beyond the edge of the solar system. This could explain the recent discovery of a "giant ribbon" in space by NASA's IBEX spacecraft.

NASA's next great observatory, the James Webb Space Telescope, is designed to study stars and galaxies. Astronomers are beginning to realize, however, that Webb will make a great planet hunter too.

Most astronomers wouldn't dream of opening their observatory's doors in 100 mph winds. Yet NASA's new SOFIA telescope recently flew in an airplane at 250 mph with doors wide open.

NASA is building a new space telescope named "NuSTAR" to answer a question that has been vexing astrophysicists for decades: Why won't the supernova explode?

NASA's Kepler space telescope, designed to find Earth-size planets in the habitable zone of sun-like stars, has discovered its first five new exoplanets.

NASA's Mars rover Spirit is about to mark six years of Red Planet exploration. However, the upcoming Martian winter could end the roving career of the beloved, scrappy robot.

Party planners take note. For the first time in almost twenty years, there's going to be a Blue Moon on New Year's Eve.

The solar system is passing through an interstellar cloud that physics says should not exist. In the Dec. 24th issue of Nature, a team of scientists reveal how NASA's Voyager spacecraft have solved the mystery.

NASA's Cassini Spacecraft has captured the first flash of sunlight reflected off a lake on Saturn's moon Titan, confirming the presence of liquid on the part of the moon dotted with many large, lake-shaped basins.

A continent-wide network of all-sky cameras has photographed a never-before-seen phenomenon: colliding auroras that produce explosions of light. The must-see images have solved a long-standing mystery of Northern Lights.

This week, researchers attending the United Nations Climate Change Conference in Copenhagen unveiled a unique web site that gathers and organizes climate data for decision makers, professional scientists and lay people.