Skywatch

  • February 2, 2006

    Episode 21: Buffy the Kuiper Belt Object

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    A new mystery is afoot in our solar system. Scientists at the Canada-France-Hawaii Telescope on Hawaii's Mauna Kea have discovered an object, about a fifth to half the size of Pluto, traveling in an orbit tilted about 47 degrees to most of the other objects in the solar system. The strange orbit is confounding astronomers. In addition to the tilt, the orbit is close to circular - odd in a solar system with mostly elliptical orbits. Scientists have tentatively named the object 2004 XR190, but nicknamed it "Buffy," after the TV show "Buffy the Vampire Slayer." Kuiper Belt objects like Buffy can acquire strange orbits by interacting with other objects - but those common explanations don't seem to apply in this case. Buffy's distance and strangely shaped orbit help rule out a close encounter with the usual suspect, Neptune. Likewise, a passing star would have given its orbit a different shape.