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KRONOS Vol V, No. 1
THE RING OF COMETS AND METEORITES ENCIRCLING JUPITER
S. K VSEKHSVYATSKII
Editor's Preface : On March 7, 1979, a faint ring of dark rocky debris was discovered circling the giant planet Jupiter in its equatorial plane. The discovery was made by Voyager 1. The ring, which is situated some 34,000 miles above the upper deck of Jupiter's multicolored clouds, is estimated to be less than 18 miles thick and more than 5,000 miles wide. (Saturn's rings are only 10 miles thick but almost 170,000 miles wide.) American scientists had not expected the discovery and could only speculate on the possible cause of the ring. In the words of Dr. Bradford A. Smith, head of the Voyager photography team: "Now Jupiter is found to have a ring and we must invent a theory to explain it. "
Two months after the discovery of the ring around Jupiter, the Soviet Union claimed joint credit for the discovery, contending that a Russian scientist predicted the ring's existence as early as 1960. Dr. Viktor A. Ambartsumyan, director of the Byurakan Observatory in Soviet Armenia, cited the earlier theoretical work of Prof. S. K. Vsekhsvyatskii whose prediction of a ring around Jupiter was first published in 1960 in a journal called Izvestia of the Armenian Academy of Sciences (Physical-Mathematical Series).
Ambartsumyan quoted the following passage from the relevant paper by Vsekhsvyatskii: "The existence of active ejection processes in the Jupiter system, demonstrated by comet astronomy, gives grounds for assuming that Jupiter is encircled by comet and meteorite material in the form of a ring similar to the ring of Saturn."
Despite the fact of his priority, Vsekhsvyatskii's name has remained conspicuously absent from the scientific literature pertaining to Jupiter. It is to be hoped that the appearance in KRONOS of the following material by the Russian astronomer will rectify this situation to a considerable extent. – LMG
Visual observations of the planets, such as Jupiter, Saturn, and their satellites, indicate that processes of an eruptive or volcanic nature (white spots, the red spot, the volcanos of Rees(e), changes on the surfaces of the satellites, etc.) occur on these celestial bodies. This is also confirmed by the bursts of radio-emission linked to the active regions of Jupiter.
The existence of short-period comets, with their recent origin and planetary motion, shows that the ejection of meteoric material and ice masses is taking place at the present time in the systems of Jupiter and Saturn. The masses of ejected material, with their velocity less than that which produces comets and meteoric bodies on heliocentric orbits, will not be capable of leaving the gravitational field and must form the satellite system. One should thus expect the formation of rings, composed of comet-meteorite fragments, ash particles, and gas, circulating within the equatorial plane of the planet. In terms of their structure and spectrum, the rings of Saturn would be of such a nature.
Observations of the rings of Saturn show numerous changes (the appearance and disappearance of the divisions and of the transparent condensations, the luminescence at the edge of Ring A, the variation in brightness of Ring C, etc.)(1) which indicate that the evolution is rapid and that activity persists even into the present. The observational data refute the opinion that the ejected masses cannot achieve the required angular momentum. Neglected here are ejections from the satellites, the influence of the planet's magnetic field, mutual collisions of the fragments, the influence of the already existing ring, the influence of the satellites, and other effects. Not only the ring of Saturn argues in favor of this fact, but also the existence of the ring of particles encircling the Earth and the gas rings around many non-stationary stars.
Based on the findings of O. Struve(2) and on observations made later, there are indications that the center line of the rings has moved about 9000 kilometers closer to the surface of the planet (0.15 of the radius of the planet). If this corresponds to the center of distribution of mass, we conclude that the reduction in the total mechanical energy of the ring is about 1036 ergs. The energy should have been dissipated considering the mutual collisions of the fragments of the ring and the resistance of the gaseous medium.
In the light of these findings, the existence of a comet-meteorite ring encircling Jupiter seems very probable. In view of this, numerous illustrations of Jupiter have been examined with special attention to the aspect and peculiarities of the equatorial band usually situated in the middle of the light-colored equatorial zone of the planet. The equatorial band has been recorded by observers since the middle of the last century. Series of observations by Lohse, Flammarion, Nijland, and members of the British Astronomical Association and others, obtained during more than 80 years, have shown that the periods of stable visibility of the band correspond to the time of the maximum zenographic latitude of the Sun (Dc) and of Earth (Dt). This conforms to the supposition that the equatorial band of Jupiter is the shadow of the ring circling the planet. Such a conclusion is confirmed by examining the position of the band on the disk and by its non-homogenous structure during periods close to small Dc. From the illustrations by Lohse, Nijland, the British Astronomical Association observers and others, as well as from photographs obtained with the Mt. Wilson telescope, the positions of the band relative to the center of the disk a have been determined. These positions were compared to the Dc values. A definite relationship was established: a = k Dc; the values k = -1.38 ± 0.27 and k = -1.50 ± 0.3 depend on different methods for solving the equations.
But a similar connection must take place in the case where the shadow of the ring is situated in the equatorial plane of the planet. The a values and evaluations of the width of the equatorial band (= 2, in the case Dc = 3) give the height of the ring within the limits 1.4-1.0 of the radius of Jupiter; the inner rim of the ring is at a height of 0.6-0.3 of the radius.
Observations with large telescopes can confirm the existence of the hypothetical ring of Jupiter. It appears that the problem can be resolved by three possible methods: 1) it is necessary to evaluate the position and width of the equatorial band; 2) it is necessary to establish the existence of the ansae of the ring – under analogous conditions they are just as invisible as those of Saturn (small Dc and Dt); 3) it is necessary to evaluate the velocity of the rotation of individual features of the equatorial band, only fragments of which are often seen. If the equatorial band is the shadow, the angular velocity has to be 1.5-2.0 times greater than that of the individual features of the disk.
Comparison of the darkening of the shadow of the ring of Saturn, at the moment of its disappearance, and the equatorial band of Jupiter shows that the brightness of the ansae of the ring of Jupiter may be some ten times less than the brightness of the ansae of Saturn under analogous conditions.
1. T. E. R. Phillips, Monthly Notices of the Royal Astronomical Society, V. 69
(1908) p. 39; E. E. Barnard, M. N., V. 69 (1909), p. 621.
1. S. K. Vsekhsvyatskii, "Possible Existence of a Ring of Comets and Meteorites
Around Jupiter," Soviet Astronomy – AJ, Vol. 6, No. 2 (Sept.-Oct., 1962),