Small World Spotted Far Beyond Pluto

Scott S. Sheppard: Carnegie Institution for Science

ScienceShot: Small World Spotted Far Beyond Pluto

Astronomers have detected a small world (inset) more than twice as remote as Pluto, lying 12 billion kilometers, or 83 AU, from the sun. (One AU, or astronomical unit, is the mean sun-Earth distance.) As scientists report online today in Nature, the new object is the first ever found whose orbit (red curve) resembles that of Sedna (orange curve), a far-off body that never gets close to Neptune's path (outermost magenta circle). Both Sedna and the new world, designated 2012 VP113, therefore differ from Pluto and other members of the Edgeworth-Kuiper belt (turquoise dots), which lie just past Neptune's orbit. The object journeys 80 to 452 AU from the sun, never approaching Neptune (30 AU) or Pluto (39.5 AU). The new world is roughly 450 kilometers across, just one-fifth Pluto's diameter. If Pluto were as big as a basketball, Sedna would be a softball and the new world a mere golf ball. Whereas Pluto orbits the sun every 248 years, the new world requires 4340 years and Sedna 12,600 years to do the same. Both Sedna and its small sidekick probably belong to the inner part of the Oort cloud, the frigid reservoir of long-period comets that can dazzle us when they dash toward the sun, and suggest that many other far-flung objects await discovery.

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Posted in Space