New calculations reveal that large planetoids may have formed hundreds of times farther from the Sun than previously thought. One such object, Sedna, discovered in 2003, is close to the size of the outermost planet, Pluto. Alan Stern, director of space studies at the Southwest Research Institute, suggests that Sedna may have formed at its current distance, or even further out. Sedna has a highly elliptical orbit; at its furthest, Sedna will be about 940 times further from the Sun than the Earth (940 AU). Stern says Sedna may have been born in a circular orbit at about 500 AU; it's current elliptical orbit is probably the result of a close encounter with a passing star or another large body in orbit around the Sun.

Stern's work is the latest in a series of speculations by scientists to try to explain the find. Some believe that Sedna is a Kuiper Belt object (formed within the orbit of Neptune); others believe that Sedna is an inner Oort cloud object. Scientists have also advanced the theory that Sedna was not created in this solar system at all, but was pulled from a passing star early in the formation of the solar system.


Sedna, we're glad we met ya! Hey, it's easier to pronounce than that
other space rock's name, Quaoar. Oh yeah, that just rolls off the tongue.

The idea of a planet that passes from star to star has also been explored in science fiction. In his excellent 1977 novel Dying of the Light, George R.R. Martin writes about a world named Worlorn, a rogue planet discovered by the race of Man in the distant future. When the path of the object was plotted, it was clear that it would make a single close approach to the Hellcrown, a multiple star system. Fifty standard years of sunlight would briefly warm this wandering world, the venue for the greatest festival ever held...

There was a century of storms as Worlorn neared the light: years of melting ice and volcanic activity and earthquakes. A frozen atomosphere came, bit by bit, to life and hideous winds howled like monster infants. All this the outworlders faced and fought.

The terraformers came from Tober-in-the-Veil, the weather wardens from Darkdawn... The men of High Kavalaan supervised it all, since High Kavalaan claimed the rogue... At last Worlorn was gentled. Then cities rose, and strange forests flowered ... and animals were set loose to give the planet life.

In ai-589 the Festival of the Fringe opened.. On that first day the Toberians let their stratoshield shimmer, so the clouds and the sunlight ran and swirled in kaleidoscope patterns. Other days followed, and the ships came...
(From Dying of the Light)

Martin creates a great story of lost love and changing cultures in the novel; it also contains lots of original technology, like the sky-scoots (anti-gravity flying carpets) and High Kavalaan aircars. Dying of the Light was reissued last year in paperback, and I highly recommend it.

Read more about new work on Sedna at Solar system planetoids could be really far out; read more about Sedna at Space.com. See Stay star may have jolted Sedna for alternative views on the formation of distant planetoids.

(This Science Fiction in the News story used with permission from Technovelgy.com - where science meets fiction.)