Far-out science
By Ron Cowen
When scientists announced last year that they had discovered the most-remote object known in the solar system, they reported that the icy body probably had a moon. That’s because the object, named Sedna, seemed to spin unusually slowly, just once every 20 days. Only the tug of a small companion body could slow the rotation to such a leisurely rate, the astronomers reasoned.
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2005/04/4963.jpg?resize=150%2C96&ssl=1)
The Hubble Space Telescope, however, failed to find a moon (SN: 4/24/04, p. 262: Puzzle on the Edge: The moon that isn’t there). Now, new measurements show that Sedna rotates some 50 times as fast as earlier observations indicated.