- by Juan Revilla
The recent discoveries of the last decade, such as the trans-Neptunian asteroids and the centaurs, have challenged traditional speculations about alleged large planets beyond Pluto, and have also resulted in a new picture of the solar system which differs from the one traditionally taught at school and still dominant in the mind of many astrologers.
There are several facts that seem to break the schematism that would like to find "Planet X" and planet "Y" beyond Pluto in order to have a perfect system of 12 major planets. The first of these facts is the nature of Pluto, which physically and dynamically belongs more properly to the world of minor planets, and poses astronomers with a problem of definition and classification: what is a "major" planet and what is not? When a planet is "major" or "minor"?
Pluto has always been a mystery, both to astronomers and astrologers, but it seems to me that the centaurs --his offspring in many ways-- are bringing Pluto closer and closer to us. For example, a few months after the discovery of Chiron, in 1978, Pluto's moon Charon was found, which allowed a more precise determination of its mass and size. It became clear then that Pluto was the smallest of all the planets in the solar system, and that it had been discovered by "chance" or serendipity.
Recent photographs taken by the Hubble Space Telescope have allowed a more precise knowledge of the relative sizes of Pluto and Charon. The diameter of Pluto is estimated to be 2320 Km, and that of Charon 1137 Km. With a Moon that is only half its size, Pluto is really a binary object half-way between the major and minor planets. No other major planet in the solar system has this binary quality except Earth, but in this case the Moon is 1/3 the size and the mass is 1/81th, while the mass of Charon is between 1/6th to 1/12th the mass of Pluto, and is by far the largest (comparatively) satellite in the solar system.
Pluto's elongated orbit is identical to hundreds or thousands of smaller proto-planets or planetesimals that share the same orbital space around the Sun, like an orbital ring in resonance with Neptune, called "plutinos". Nearly 80 plutinos have been found, all of them differing from Pluto only by their smaller size. The largest plutino so far, temporarily called "2001KX76" and about the same size of Charon (1/2 of Pluto), is the largest minor planet ever found and establishes a physical continuity in size between Pluto and the ring of plutinos sharing its orbit.
Pluto is really in an intermediary position between the world of asteroids or minor planets and that of the "major" planets. Many astronomers think that soon there will be a time when considering Pluto as a major planet will be a thing of the past. It challenges that type of thinking among astrologers which considers "size" as synonym with importance or "weight", and who use that as criterion for choosing what to include and what to exclude from an astrological chart.
Beyond Pluto there is the classical "Kuiper Belt" or "Cubewanos", of which around 280 have been discovered now, some of them with probable diameters of up to 1000 Km, and with more circular and stable orbits, very different to those of Pluto and the plutinos. The object named "Varuna" is the second largest known minor planet, and is representative of these bodies, which are a different category altogether from what is usually called "asteroids", between Mars and Jupiter
Beyond the Cubewanos is the so-called "scattered disk", which surrounds the solar system like an enormous primal elliptical cloud where the "scattered disk objects" have their home (such as 1996TL66, with about 500 Km in diameter), with periods extending 1000 years and reaching the "Neptune barrier" or frontier without trespassing it, only to go away to distances never before imagined in a minor planet, of up to 10 times Neptune's solar distance, and return like resurrected mummies from other epochs. They represent a new type of orbits that was not even suspected before their discovery.
TCentaurs are probably scattered disk objects that have been captured; their orbits are "chaotic" (they are not periodic in the long range) and they cross like giant comets the space occupied by the outer planets, violating the traditional (or "classical") ways of moving of the major planets (minus Pluto). Pluto, crossing the orbit of Neptune, psychologically penetrating and obsessive, in proximity to death, had been their forebearer.
- :::continued next page:::