The Solar System in which Earth is the third planet out from the Sun suddenly increased in size tremendously four months ago when a never before seen reddish object located eight billion miles from Earth was discovered in November 2003 by scientists using the old reliable Palomar telescope located on a California mountain peak. The object has been named "Sedna" and is thought to be a planetoid similar (but not exactly like) a planet.

However, I think it is more likely to be a dusty iceball that originated by the Oort Cloud, a huge roughly spherical shell comprised of trillions of primordial dusty iceballs that completely surround the Sun and the planets - which along with the dusty iceballs in the Kuiper Belt, are remnants of the huge nebula from which the Sun and the planets formed 4.6 billion years ago. The rock-dust ice particles in both groups of dusty iceballs are gravitationally tied to the Sun and orbit around it at much slower velocities than do the Solar System planets (the velocity of orbiting objects about the Sun is inversely proportional to their distance from the Sun: the less the distance, the more the speed and vice versa).

Sedna was named by its lead discoverer, Michael Brown, a Caltech astronomer, after the Eskimo goddess whom the Inuit consider to have created all the Arctic sea animals that the Eskimos depend on in order to survive in their frigid icy habitat. The roughly spherical amoeba-shaped Oort Cloud of dusty iceballs was named after the Dutch astronomer Jan Oort who predicted its existence back in 1950, and the Kuiper Belt (discovered in 1992) was named after Gerard Kuiper, another Dutch astronomer who predicted its existence in 1951.

Both the Oort Cloud and the Kuiper Belt are postulated to be the major sources of comets - which consist of discrete dust and ice particles that travel through space together in highly elliptical orbits that bring them closest to the Sun at one point in their orbits and farthest out from the Sun at another point located halfway round the orbit directly across from the closest point. Comets do not have tails unless they are close enough to the Sun for the solar wind to blow some of the dusty iceball's outer layer away in the direction opposite the Sun to form a tail. The tail lengthens as the comet moves toward the Sun and shortens as it moves away - until it disappears about five Earth-Sun distances out from the Sun (the average radius of Jupiter's orbit).

We can distinguish dusty iceball comets that had orbited within the Oort Cloud for approximately 4.6 billion years before being perturbed (diverted) out of their normal placid, nearly circular orbits billions of miles out in space - from those dusty iceball comets which had spent billions of years in nearly circular orbits about the Sun in the Kuiper Belt (before being similarly perturbed by a chance passing massive object from still farther out in space) by the angle between the comet's orbital plane and the solar system's average planetary orbital plane about the Sun. A small angle between the two planes indicates a Kuiper Belt source because the Kuiper dusty iceball comets normally orbit in or close to the Ecliptic (the Solar System's planetary orbital plane). The Kuiper Belt starts just beyond Neptune's orbit and extends out to an as yet unknown distance from the Sun far beyond Pluto's average orbital position.

Alternatively, a large angle between a comet's orbital plane and the ecliptic indicates a probable Oort Cloud source for the primordeal dusty iceball comet because objects in the Oort Cloud normally orbit the sun at all possible angles to the Ecliptic plane. When additional Sedna-like objects are discovered and their orbital characteristics determined in the future, we will be able to ascertain more precisely whether they came from the Oort or from the Kuiper group of comets.

A subsequent column will deal with the origin of the Solar System in greater but easily understood simplified detail.