Moons

Heat from radioactive decay inside the icy Saturnian moon Enceladus shortly after its formation 4.5 billion years ago may explain why geysers are erupting at the surface today, scientists say. According to the theory, reported Monday at the annual Lunar and Planetary Science Conference in Houston, Enceladus formed by the mixing of ice and rock containing radioactive isotopes of aluminum and iron.

Geysers on the little moon Enceladus are weighing down Saturn's magnetic field so much that the field is rotating slower than the planet, Iowa researchers reported Friday in the journal Science. The phenomenon makes it nearly impossible to measure precisely the length of the Saturn day using normal techniques. A Saturn day is about 10.5 hours. Gas particles emitted by the geysers form a doughnut-shaped torus of ionized gas around Saturn, exerting a drag on the planet's magnetic field.

Aristotle took note of this celestial happening a couple of millenniums back. Ben Franklin bagged a sighting or two, as did Mark Twain. The venerable John Muir, chronicler of Sierra mountaintop and meadow, waxed enthusiastic about the nighttime phenomenon. The hunt for the elusive "moonbow" has long been a nocturnal lure for dreamy hikers, insomniac seamen and intrepid photo buffs.

Images from NASA's Cassini spacecraft show that Saturn's moon Enceladus may have liquid water erupting from giant Yellowstone-like geysers, raising the tantalizing possibility that the icy moon could support some form of life, scientists said Thursday. "We realize that this is a radical conclusion," said Carolyn Porco, a researcher at the Space Science Institute in Boulder, Colo., and head of the Cassini imaging team.

Pluto's two newly discovered moons have been named Nix and Hydra, scientists said Thursday. The official designations for the second and third moons around the distant planet were approved by the International Astronomical Union. Nix and Hydra were discovered in May 2005 by a team of researchers using the Hubble Space Telescope. Nix gets its name from Nyx, the Greek goddess of darkness and night.

British and U.S. scientists said Friday that they were exploring plans for a joint lunar mission that would fire missile-like penetrators into the moon's surface. The Moon Lightweight Interior and Telecoms Experiment, or MoonLITE, would put a satellite into orbit around the moon. Three or four projectiles packed with scientific instruments would then be fired and embed just below the lunar surface, the British National Space Center and NASA said. MoonLITE could deliver important information about the moon's structure, such as the size of the lunar core and the source of lunar seismic activity.

Saturn's second-largest moon, Rhea, may have a small ring around it -- the first time a moon has been found to have a ring, an international team of researchers reported Friday in the journal Science. The four largest planets in the solar system -- Jupiter, Neptune, Saturn and Uranus -- have rings, and Earth probably had one as well at some point billions of years ago.

By Kevin, 10 Brywood Elementary Irvine Under the Coat The sky wears a black coat with buttons of glittering stars, and inside the coat, giant suns shine on small planets that swirl night and day. Moons dance around their floating spheres. Asteroids of ice drift past, brushing against each other, 'cause there's bad traffic in this highway of stone cars. And on one silvery gray rock, an American flag stands alone on a moon that dances around a blue and green swirling planet.

A New Year's Eve flyby of Saturn's small moon Iapetus by the Cassini spacecraft has revealed a huge ridge along the moon's midsection. In places the mountains reach 12 miles, more than twice as tall as Mt. Everest. The mountains are almost as tall as Olympus Mons on Mars, although Iapetus is one-fifth the size.

The Cassini spacecraft, which has been unveiling the secrets of Saturn's giant moon Titan, has found an atmosphere on a second moon circling the ringed planet. The discovery of an atmosphere around the icy moon Enceladus is perplexing scientists because, at 310 miles in diameter, it had been considered too small to hold on to an atmosphere. Scientists discovered something unusual was going on at Enceladus on March 9, when Cassini approached to within about 300 miles of the surface.