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The dwarf planet Pluto and its system of five moons are about as mysterious as the underworld of antiquity that inspired their names. ... “We are still baffled by how the system formed,” says study co-author Mark Showalter, a senior research scientist at the Search for Extraterrestrial Intelligence (SETI) Institute. “I think everyone believes that, at some point in the distant past, a large object bashed into ‘proto-Pluto’ and the moons formed out of the debris cloud. However, after that point in the story, details get very sketchy.” Now, analysis of data collected from the Hubble Space Telescope following the...

Scientists used to think that things were pretty chill over in the south hemisphere of Uranus. In fact, they thought it was one of the calmest regions of any of the gas giants. But in analyzing images taken nearly three decades ago by NASA's Voyager-2 spacecraft, researchers think they've found a kerfuffle of activity — which might indicate that there's something unusual about the planet's interior. If you look at these old photos of Uranus, the planet appears to be a stark, featureless ball. And even to scientists, who were able to identify more lively features of the gas giant,...

Martin Bizzarro of the University of Copenhagen and his colleagues set out to determine the amount of iron in the early solar system. To do so, they measured nickel-60, a decay product of iron-60, in eight meteorites known to have formed at different times during the first 3 million years of the solar system. The meteorites that formed more than about a million years after the start of the solar system contain significantly more nickel-60 than do those that formed earlier, the team found. In a neighborhood of young stars, only a supernova could have produced iron-60, the parent of...

Proposed by British scientists as a joint effort of NASA and the European Space Agency, the mission would offer the first close-up view of Uranus in 25 years.British space scientists are leading plans to send a probe to explore giant ice planet Uranus. They have put forward a detailed proposal to the European Space Agency to launch a joint mission with NASA to the distant world, 1.8 billion miles from the sun. It would give scientists their first close-up views of Uranus since NASA’s Voyager 2 flew past and captured fleeting pictures 25 years ago. The £400million mission is designed...

Are comets born in great swarms? The puzzling abundance of comets in short solar orbits has led a pair of astronomers to suggest that they are fragments of larger bodies that crumbled as they entered the inner solar system. Short-period comets take less than 200 years to circle the sun and are thought to originate in the Kuiper belt of icy objects beyond Neptune. Some Kuiper-belt objects (KBOs) are in vulnerable orbits that allow the gravity of the outer planets to tug them inwards, where the sun's heat turns them into comets. However, there seem to be too few KBOs...

Enlarge ImageIt's relative. Astronomers have been measuring spin precession in an eclipsing pair of pulsars.Credit: Daniel Cantin/McGill University As if his reputation needed cementing, astronomers have confirmed Albert Einstein's status as a supergenius once more. Studying a unique pair of pulsars--small and extremely dense leftovers from supernova explosions--researchers have measured an effect that was predicted by Einstein's 92-year-old general theory of relativity. The result, they report tomorrow in Science, is almost exactly what the famous physicist had foreseen. In Einstein's relativistic universe, matter curves space and slows down time, and the speed of light remains the only constant. But...

Astronomers using NASA's Spitzer Space Telescope have found evidence that dusty disks of planet-forming material tug on and slow down the young, whirling stars they surround. Young stars are full of energy, spinning around like tops in half a day or less. They would spin even faster, but something puts on the brakes. While scientists had theorized that planet-forming disks might be at least part of the answer, demonstrating this had been hard to do until now... Stars begin life as collapsing balls of gas that spin faster and faster as they shrink, like twirling ice skaters pulling in their...

Asteroid Vesta: The 10th Planet? Discovery Brightens Odds of Finding Another Pluto Nemesis: The Million Dollar Question HOUSTON, TEXAS -- Our solar system may have had a fifth terrestrial planet, one that was swallowed up by the Sun. But before it was destroyed, the now missing-in-action world made a mess of things. Space scientists John Chambers and Jack Lissauer of NASA's Ames Research Center hypothesize that along with Mercury, Venus, Earth, and Mars -- the terrestrial, rocky planets -- there was a fifth terrestrial world, likely just outside of Mars's orbit and before the inner asteroid belt. Moreover, Planet V...

Jafar Arkani-Hamed of McGill University discovered that five impact basins--dubbed Argyre, Hellas, Isidis, Thaumasia and Utopia--form an arclike pattern on the Martian surface. Three of the basins are well-preserved and remain visible today. The locations of the other two, in contrast, were inferred from measurements of anomalies in the planet's gravitational field... a single source--most likely an asteroid that was initially circling the sun in the same plane as Mars--created all five craters. At one point the asteroid passed close to the Red Planet... and was broken apart by the force of the planet's gravity. The resulting five pieces subsequently...

New Theory: Catastrophe Created Mars' Moons By Leonard David Senior Space Writer posted: 07:00 am ET 29 July 2003 PASADENA, California – The two moons of Mars – Phobos and Deimos – could be the byproducts of a breakup of a huge moon that once circled the red planet, according to a new theory. The capture of a large Martian satellite may have taken place during or shortly after the formation of the planet, with Phobos and Deimos now the surviving remnants. Origin of the two moons presents a longstanding puzzle to which one researcher proposed the new solution at...

Probe to 'look inside' asteroids By Paul Rincon BBC News Online science staff in Paris, France Studies of asteroids would aid Earth-protection strategies A new space mission concept unveiled at a Paris conference aims to look inside asteroids to reveal how they are made. Deep Interior would use radar to probe the origin and evolution of two near-Earth objects less than 1km across. The mission, which could launch some time later this decade, would also give clues to how the planets evolved. The perceived threat of asteroids colliding with our planet has renewed interest in space missions to understand these...