just a bump to an old topic, with a link to one much older:
Big-orbit Object Confounds Dynamicists
Source: Sky & Telescope Magazine
Published: Thursday, April 5 2001 Author: J. Kelly Beatty
Posted on 04/07/2001 11:46:54 PDT by vannrox
http://www.freerepublic.com/forum/a3acf609e1367.htm
Distant planetoid Sedna gives up more secrets
New Scientist | 4/15/05 | Maggie McKee
Posted on 04/16/2005 2:23:49 AM EDT by LibWhacker
http://www.freerepublic.com/focus/f-news/1384847/posts
"Astronomers have struggled to explain such an extreme orbit, but many believe a star passing by the Sun about 4 billion years ago yanked the planetoid off its original, circular course."