Outer solar system

  • Two Ring Systems Better Than One
    NASA's Hubble Space Telescope photographed a new pair of rings around Uranus and two new, small moons orbiting the planet. The largest ring is twice the diameter of the planet's previously known rings. The rings are so far from the planet, they are being called
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  • The Ice Dwarf Cometh
    The New Horizons spacecraft, scheduled for launch in mid-January, will investigate the far-off planet Pluto and its icy moons. This will be the first spacecraft to study the Pluto system, as well as the mysterious outer region of our solar system
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  • Kuiper Belt’s Quadruple
    A team of astronomers at Southwest Research Institute (SwRI) and other institutions has discovered that Pluto has two previously unseen moons. Ground-based observers discovered Pluto's only previously known moon, Charon, in 1978. The planet itself was discovered in 1930.
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  • Kuiper Belt Adding to its Notches
    The newly discovered 10th planet, 2003 UB313, is looking more and more like one of the solar system's major players. It has the heft of a real planet (latest estimates put it at about 20 percent larger than Pluto), a catchy code name (Xena, after
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  • Santa et al.
    When planetary scientists announced on July 29 that they had discovered a new planet larger than Pluto, the news overshadowed the two other objects the group had also found.
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  • Tenth Planet
    A planet larger than Pluto has been discovered in the outlying regions of the solar system. The planet is a typical member of the Kuiper belt, but its sheer size in relation to the nine planets already known means that it can only be classified
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  • Charon’s Occultation
    In a feat of astronomical and terrestrial alignment, a group of scientists from MIT and Williams College recently succeeded in observing distant Pluto's tiny moon, Charon, hide a star. Such an event had been seen only once before, by a single telescope 25 years
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  • Voyager I Reaches Final Frontier
    NASA's Voyager 1 spacecraft has entered the solar system's final frontier. It is entering a vast, turbulent expanse, where the sun's influence ends and the solar wind crashes into the thin gas between stars.
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  • Pluto’s Pair
    The evolution of Kuiper Belt objects, Pluto and its lone moon Charon may have something in common with Earth and our single Moon: a giant impact in the distant past.
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  • Planetoids Beyond Pluto
    Counting down the top ten astrobiology stories for 2004 highlights the accomplishments of those exploring Mars, Saturn, comets, and planets beyond Pluto. Number six in this countdown was the discovery of potential heat sources for ice beyond Pluto, an important finding if water is considered
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  • What Melted the Ice Planet?
    In October 2002, the Hubble Space Telescope first spotted an icy planetoid beyond Pluto. Named after an American Indian god, Quaoar, the planetoid should be far colder based on its distance from the sun than it appears to be.
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  • Vision of Neptune’s Triton
    Beyond the gas giants of Saturn and Jupiter, NASA plans its vision to explore the ice giants, like Neptune. While Titan attracts all the attention of moon watchers near Saturn, Triton intrigues those looking near Neptune.
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  • Stormy Uranus
    As the smallest of the gas giants, Uranus was thought from the Voyager probe flyby to have a relatively inactive surface. Stunning new images reveal storms the size of entire terrestrial continents and a faint ring.
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  • Beyond the Nine Planets
    The first detection of the faint distant object dubbed "Sedna" beyond Pluto may represent a new planet-like body with a moon. Looking up from Sedna's surface, the Sun would appear in the sky as the size of a pinhead.
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  • New Moon System Around Uranus
    Using the Hubble Space Telescope, astronomers have found two of the smallest moons yet in the Uranus satellite system. Measuring a minute eight miles, two of the small moons had previously eluded detection from the much closer view offered from the Voyager 2 flyby of
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