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Beyond Earthly Skies

Drifter in the Dark

7 Sep 2013, 22:00 UTC
Drifter in the Dark
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The Inner Oort Cloud (IOC) is a region of space that lies beyond the Kuiper Belt. Objects presently known to be part of the IOC have highly elongated orbits that never come close enough to the Sun for their orbits to be dynamically influenced by gravitational interactions with Neptune. These objects have semi-major axis ≥ 200 AU (average distance from Sun) and perihelion ≥ 44 AU (minimum distance from Sun). Due to their great distance and faintness, only a few IOC objects are presently known - 2000 CR105 (Gladman et al. 2002) with perihelion 44.1 AU and semi-major axis 228.8 AU; Sedna (Brown et al. 2004) with perihelion 76.2 AU and semi-major axis 542.7 AU; and 2004 VN112 (Becker et al. 2008) with perihelion 47.3 AU and semi-major axis 343.3 AU.These four panels illustrate the orbit of Sedna - an IOC object which lies in the farthest reaches of the Solar System. Each panel, moving clockwise from the upper left, successively zooms out to place Sedna in context with the Solar System.One or more mechanisms triggered by external perturbations must have produced the large perihelion distances and highly elongated orbits of the IOC objects. Proposed scenarios include interactions with a ...

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