Outer solar system

  • Capturing Triton
    Neptune's large moon Triton may have abandoned an earlier partner to arrive in its unusual orbit around Neptune. Triton is unique among all the large moons in the solar system because it orbits Neptune in a direction opposite to the planet's rotation (a "retrograde" orbit).
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  • Hubble Spies Pluto’s New Moons
    The Kuiper Belt is a band of icy, rocky objects and dwarf planets that orbit the Sun in the outer region of our solar system, beyond the orbit of Neptune. It has been known since 1992; Pluto is its most prominent member. Using the
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  • To Pluto and Beyond
    As the New Horizons mission to Pluto prepared for launch in January, NASA presented a webcast in which mission scientists answered questions from the public. In this edited transcript, project scientist Harold Weaver Jr. talks about what we could learn about Pluto.
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  • Questioning Pluto
    As the New Horizons mission to Pluto prepared for launch in January, NASA presented a webcast in which scientists answered questions from public. In this edited transcript, David Kusnierkiewicz, mission systems engineer for New Horizons, talks about technology that will take spacecraft
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  • New Horizons mission to Pluto launched
    The New Horizons mission launched from Cape Canaveral, Florida at 2 p.m. Eastern time this afternoon. The spacecraft is now headed to the planet Pluto, speeding from Earth at 8 miles per second. Because Pluto is so far away, it will take New
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  • Moons Over the Kuiper Belt
    In the not-too-distant past, the planet Pluto was thought to be an odd bird in the outer reaches of the solar system because it has a moon, Charon, that was formed much like Earth's own moon was formed. But Pluto is getting a lot of
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  • Sizing Up the Ferryman
    Being in the right place at the right time gave a group of Massachusetts research astronomers a unique opportunity to study Pluto's largest moon Charon. The resulting measurements, to unprecedented accuracy, of Charon's size and possible atmosphere provide insight into the way this distant world
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  • Pluto… Brrrr!
    Mercury is boiling. Mars is freezing. The Earth is just right. When it comes to the temperatures of the planets, it makes sense that they should get colder the farther away they are from the Sun. But then there is Pluto. It has been suspected
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  • Reading Space Dust
    The University of Colorado at Boulder's long heritage with NASA planetary missions will continue Jan. 17 with the launch of a student space dust instrument on the New Horizons Mission to Pluto from Florida's Kennedy Space Center.
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  • 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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