New Discoveries Beyond the Neptune and the Pluto Orbit © Robert von Heeren, Munich 1994-1998 (Translator: Kirstin Heimerl) This english version of my german article (1) was published in "The Mountain Astrologer"-magazine in 1/1996 (The mentioned tables and figures are not shown here, because you find them updated at my astrology-page. See: Neue Planeten) There is more news from the border of the Solar System: so far 11 trans-Neptunians (Table 2) and a further 16 trans-Plutonians (Table 1) have been brought to light (as at: October 1995) since the spectacular discovery of a trans-Plutonian miniplanet by Jewitt and Luu with the Mauna Kea Telescope at Hilo, Hawaii on August 30, 1992 (3; click here for the discovery chart of 1992 QB1). Its provisonal designation is "1992 QB1" (2). The discoveries of all this planets partly confirm the theory promulgated by the Dutch-American astronomer Gerard Kuiper (12/7/1905-12/23/1973) in 1951 (4). He assumed that a ring of comet-like matter, so-called Planetesimals, could exist beyond Neptune, which was left when the planets formed over 4 billion years ago. The existence of such a "Kuiper-belt" or "Kuiper-disk" (surrounding the whole Solar System) would explain the partly unknown origin of many comets: through collisions and orbit disturbances (caused by Neptune's gravity) within the belt isolated fragments would reach the interior of the Solar System as comets or unusual minor planets on more or less eccentric and unstable orbits. According to spectral analysises the currently known 28 Kuiper-belt objects do NOT seem to be comets, but they nonetheless belong to the Kuiper-belt. W hen comparing their spectra with other minor planets, moons and asteroids within the Solar System no conformity was to be found. So the new planets obviously form a new independent group of minor planets, nicknamed the "icy dwarfs", which are of course of great interest to astronomers. Scientists are hoping, among other things, to gain important information about the structure of the Kuiper-belt and the dynamics of the outer Solar System from their research. It is very likely that there are considerably more minor planets (6; perhaps more then 10.000) with a diameter between 1 and approx. 300 km beyond Neptune and Pluto. Maybe some of them even reach 1.000 km in diameter! Pluto with its 2.320 km diameter (7) is and will probably always be the "King" (5) of the Kuiper-belt, similar to the biggest asteroid Ceres (930 km), which is the "Queen" of the inner asteroid belt. The discovery of the new minor planets is already comparable in its significance for astronomy to the discovery of Ceres, Pallas, Juno, Vesta and the inner asteroid belt objects at the beginning of the last century. As yet not much is known about the physical composition of the trans-Neptunians and the trans-Plutonians. At distances between 4.5 and 7 billion kilometres (approx. 30-47 astronomical units) and a very weak albedo, they are extremely hard to observe even with the newest electronic detection methods (e.g. CCD). Some of the new planets (e.g. 1992 QB1) shows a very strong reflection in the infrared zone (similar to Pholus). That is an indication of dark organic carbon compounds, which could be the reason for their very weak albedo. The other objects seem to be more Chiron-like (8), without special spectral features, as it could be said from the few observations till now. From the measured "light intensity" the diameter of 1992 QB1 has been estimated to be approx. 200-250 km (9), which is about an eighth of Pluto's diameter. The other new planets are roughly of the same size. Objects of comparable size in the Solar System are e.g. the centaurs Chiron (10) (between 83 and 156 km) and Pholus (140 km) (11), as is the asteroid Juno (244 km). However they do have completely different orbits from the trans-Neptunians and trans-Plutonians. As far as it could be established from the measurements till now, the orbits of the most trans- Plutonians seem to be nearly circular and stable in contrast to Chiron and Pholus. The orbits of the most trans-Neptunians seem also to be stable because of stabilising resonances in respect to Neptune. The trans-Neptunians 1993 RP, 1993 RO, 1993 SC, 1994 TB, 1994 JR1, 1995 HM5, 1995 GA7 and 1995 KK1 with their periods about 247 years seem to be (like Pluto!) in a stabilising 3:2 resonance in respect to Neptune (164 years). Therefore you can call them small "Plutonians", like Pluto is of course a big trans-Neptunian. This resonance effect could keep their orbits stable for million of years (12). Only the two trans-Neptunians 1993 SB and 1994 TB are Neptune-crossers (like Pluto), because of their greater eccentricities. The orbits of the other trans-Neptunians and of all trans-Plutonians are lying outside the Neptune orbit, but they are more or less crossing Pluto's orbit on the inside. There is one exception: 1994 ES2. As its orbit currently can be determined, this is the first new planet, which moves all over the time (310 years) outside the Plutoorbit (Figure 1). So it seems, that 1994 ES2 is the first real "Transpluto"! Apart from the varying orbital periods and eccentricities there are also differences in orbit inclinations: the smallest inclinations of less than 1° can be found with the trans- Plutonians 1994 EV3, 1994 ES2, 1994 GV9, 1995 FB21 and 1995 GY7. They move directly within the ecliptic. Contrary to this, the trans-Neptunians 1994 JS, 1994 JV, 1994 TB, 1994 TH and 1995 GJ have the greatest orbit inclinations between 12° and 23° among all the new planets discovered so far. However, to determine with certainty the course of the orbits and the physical properties, the new planets obviously have to be observed over a much longer period of time. To date there are somewhat more measurements (13) for 1992 QB1, 1993 FW , 1993 RO and 1993 SC (14). For these the ephemerides for the 19th and 20th century can be drawn up by numerical integration with a precision that lies within the range of arc minutes (15). Of course this is based on the assumption that the orbit theories applied in the calculations do not have to be changed considerably due to new observations. They are observed only for a very short time over their very slow and long journey through the outer Solar System! At the moment the positions of all the other Kuiper-belt planets can be calculated temporarily for a few years or even only months (e.g. 1993 RP) forwards or backwards, because for many of them the excentricities are currently unknown (assumed circular orbits). In the following three tables I would like to bring to your attention the provisonal names, the discoverers, periods, positions (according to my own calculations) and the dates of discovery of all presently known trans- Neptunians and trans-Plutonians in chronological order. The first two tables show the periods, the tropical positions at discovery and at 2/1/1996 0h UT (16), so you can see where they were at the discovery and where they are now. Table 3 provide you with all datas you need for calculating the discovery charts for all 28 new planets! Trans-Neptunians have a mean solar distance greater than Neptune's (30.10 AU) but smaller than Pluto's (39.34 AU (17)). All of the trans-Plutonians have a mean solar distance (semi-major axis) greater than 40 Astronomical Units. Why were the most of all the new planets retrograde during their discovery? The reason for this is that planets outside Earth's orbit can be observed best at the time of their yearly opposition to the sun. The further they are away from Earth, the longer their apparent motions are retrograde at opposition and the more likely their retrograde motion is at their discovery. A further interesting aspect is that nearly all the new minor planets were in the 9th or 10th house near the MC in their discovery charts. There is an explanation for this, too: the observing conditions are simply most favourable for objects at such a distance and so faint during the nucturnal culmination. Are the new trans-Neptunians and trans-Plutonians astrologically relevant at all? Of course we will only know this, when we have investigated them astrologically. In my opinion their significance for astrology should not be played down because of their small diameters, their great distances or their slow motions. Pluto, or Chiron, too, teach us repeatedly that these criteria say nothing about their astrological importance. 1992 QB1, the planet that was first of the 28 new Kuiper-belt planets to be discovered, is certainly remarkable. At its discovery on 8/30/1992 it was of all places exactly at the vernal equinox! (table 1) I could well imagine that, due to this special "pioneer" position at the beginning of Aries, it could be a guide to astrological understanding of this new group of trans-Neptunian and trans-Plutonian planets or so-called TNOs (trans-Neptunian objects). But it is too early for an interpretation. On this score we are waiting with anticipation which "proper" names the new planets will receive. Today, one thing is already certain: Pluto, with all its fascination and from time to time threat, is not the "last word" in our Solar System. After a long wait we now finally know that there is something in the Solar System beyond Pluto.