The last most of us heard, there were nine planets. However, a quick check of the Minor Planet Catalogue shows that as of last month, there are 320,000 catalogued bodies orbiting our Sun. Which of these bodies are actually planets is an issue that has been dogging astronomers for awhile. But planetary science in its current form is still fairly new. Until 1992 all we had to deal with were the "nine planets" and the asteroids.

That was the year that 1992 QB1 was discovered—the first known object orbiting our Sun beyond Pluto. This confirmed the theory of Gerard Kuiper that there was a region of space which constitutes a "comets' lair," that is, it's home to lots of little bits and bobs, relics of the early solar system. As more of these things (called Kuiper Belt Objects, or KBOs, of which there are now thousands known) were discovered, it became clear that Pluto was one of them, admittedly a large one, and this is what began the debate over "whether Pluto is a planet."

I use quotes here because this is an astrology column, so any discussion of Pluto's status being demoted is something of a joke, admittedly a not-so-funny one for those of us who are aware of having had our asses kicked by the influences of Pluto—which amounts to a little ice cube at the edge of reality. Plus, one good look at the cycles of history shows that when Pluto is active, the world changes in big ways. Two examples are the 1960s (Uranus-Pluto conjunction) and the 9/11-era (Saturn-Pluto opposition).

Yet there is a precedent for such a change of status. When Ceres was discovered in 1801, it was presumed to be a fixed star, and then considered to be a new planet (the second, after Uranus, which was discovered in 1781). The discoverer, wanting to err on the side of caution where both the public and scientific communities were concerned, announced his find as a comet, but eventually he became convinced he had discovered a small planet. Ceres is now object #1 in the Minor Planet Catalogue (MPC).

In the years that followed, several more objects in the region of space between Mars and Jupiter were discovered, and as a result, Ceres got demoted to the status of asteroid. Now, most people, including astrologers, have no idea that Ceres was ever considered a planet, and if you took a random sample of 10,000 astrology charts being worked on any given week, I would be surprised if Ceres was cast into 10 percent of them. To most astrologers, it does not exist—despite taking up 25 percent of the mass of the inner asteroid belt.

Current developments are more complex. With nearly half a million planets now included in the MPC, it's clear that the current definition of a planet is inadequate. For example, it covers a couple of hot rocks close to the Sun, Mercury (more resembling our Moon than any other planet) and Venus; our lovely green and blue home; a desert planet called Mars; and then the gas giants: Jupiter (1,300 times the size of the Earth, very nearly a brown dwarf star, with two dozen satellites); Saturn (quite similar to Jupiter, but a bit smaller); and Uranus and Neptune, the smaller of the two gas giants. Then Pluto, discovered in 1930, was included, which is quite unlike any of the others. It's a binary planet (with its counterpart Charon) around which two additional moons orbit.

It's a motley crew, to say the least, and it's clear that the definition of "planet" is either arbitrary or based on tradition; but it's not what you could call scientific.

Added to this group in recent years are several substantially large, spherical objects orbiting our own Sun beyond Pluto: Varuna, discovered in 2000; Quaoar, discovered in 2002; Sedna, discovered in 2003; and Xena (not officially named), also discovered in 2003. Chiron, which was discovered in 1977, is not a planet candidate because it's only 230 or so kilometers across, and technically classed as a very large comet nucleus—but that's only for astronomers. A fair number of astrologers have either willingly embraced Chiron, or have resigned themselves to the apparent truth that this weird little thing is here to stay.

One of the definitions of a planet that the IAU will be considering would count in Ceres, Varuna and Quaoar among the lot, and leave Pluto in its current status. Sedna would also be a likely candidate in this group. This is based on the ability of these bodies to hold their spherical shape based on their own internal gravitational force. There are other factors that may be considered, such as the angle to the ecliptic.