The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].

The solar system's largest moon, Ganymede, is captured here alongside the planet Jupiter in a color picture taken by NASA's Cassini spacecraft on Dec. 3, 2000. Ganymede is larger than the planets Mercury and Pluto and Saturn's largest moon, Titan. Both Ganymede and Titan have greater surface area than the entire Eurasian continent on our planet. Cassini was 26.5 million kilometers (16.5 million miles) from Ganymede when this image was taken. The smallest visible features are about 160 kilometers (about 100 miles) across. The bright area near the south (bottom) of Ganymede is Osiris, a large, relatively new crater surrounded by bright icy material ejected by the impact, which created it. Elsewhere, Ganymede displays dark terrains that NASA's Voyager and Galileo spacecraft have shown to be old and heavily cratered. The brighter terrains are younger and laced by grooves. Various kinds of grooved terrains have been seen on many icy moons in the solar system. These are believed to be the surface expressions of warm, pristine, water-rich materials that moved to the surface and froze. Ganymede has proven to be a fascinating world, the only moon known to have a magnetosphere, or magnetic environment, produced by a convecting metal core. The interaction of Ganymede's and Jupiter's magnetospheres may produce dazzling variations in the auroral glows in Ganymede's tenuous atmosphere of oxygen.

Nighttime clouds detected for the first time on Mars help to keep the planet’s surface warm after sunset when temperatures drop, a new study suggests. The nocturnal clouds are five times thicker than their daytime counterparts and hover close to the ground, almost like a fog.

SEATTLE--An ancient X-ray outburst from the supermassive black hole at the center of our Milky Way galaxy caused surrounding gas clouds to glow brightly in a cosmic light show that is only now being detected. The output likely involved the consumption of a snack equal in mass to the planet Mercury, researchers said here yesterday at the 209^th meeting of the American Astronomical Society. Called Sagittarius A*, the supermassive black hole at the Milky Way's core is located some 27,000 light-years away and has an estimated mass of about three million suns. It is surrounded by several massive iron-rich gas clouds that glow and emit their own X-rays when struck by photons or electrons [image].