Extrasolar Sedna

From the cool things in Nature file (yes, there will be more of these now that I've got my lovely digital subscription)--One Scott Kenyon of the SAO and Benjamin Bromley at the University of Utah have sent correspondence regarding Sedna, the Kuiper belt, and a buncha computer simulations they'd done in attempts to explain the orbital mechanics involved in the frequently inclined and eccentric orbits you usually find way out there in the burbs of the solar system. The two findings that got my attention: (1) they find the fly-by of a neighbouring star (in all probability a star formed in the same cluster as the Sun, as encounters with other stars are extremely unlikely) a plausible explanation for the peculiar shape of Sedna's orbit (such encounters had already been regarded as probable explanations for the shape and size of the Kuiper belt), and (2) they find a substantial probability (approx. 10 per cent) that Sedna was actually captured from the outer disk of the passing star:

...Although influences from passing stars could have created the Kuiper belt's outer edge and could have scattered objects into large, eccentric orbits, no model currently explains the properties of Sedna. Here we show that a passing star probably scattered Sedna from the Kuiper belt into its observed orbit. The likelihood that a planet at 60-80 AU can be scattered into Sedna's orbit is about 50 per cent; this estimate depends critically on the geometry of the fly-by. Even more interesting is the ~10 per cent chance that Sedna was captured from the outer disk of the passing star...

-- Kenyon and Bromley, "Stellar encounters as the origin of distant Solar System objects in highly eccentric orbits", Nature, December 2, 2004

Jes' think--adopted extrasolar planets in our own backyard. Relatively speaking.