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KRONOS Vol II, No. 2
THE ORIGIN AND EVOLUTION OF THE COMETS AND OTHER SMALL BODIES IN
THE SOLAR SYSTEM*Astronomical Observatory, Kiev University, Kiev, U.S.S.R.
|M (grams)||rc (g cm-3)||ER (erg g-1)|
|Sun||2.0 x 1033||1.41||9.6 x 108|
|Jupiter||1.9 x 1030||1.39||2.6 x 1011|
|Saturn||5.7 x 1029||0.71||1.7 x 1011|
|Uranus||8.7 x 1029||1.60||2.5 x 1010|
|Neptune||6.1 x 1028||1.60||1.0 x 1010|
|Earth||6.0 x 1027||5.51||3.7 x 108|
|Pluto||5.5 x 1027||10.00||9.5 x 108|
|Venus||4 9 x 1027||5.3||5.1 x 103|
|Mars||6.4 x 1026||4.00||9.4 x 107|
|Mercury||3.3 x 1028||5.80||2.1 x 104|
|Ganymede||1.6 x 1026||2.40||2.4 x 106 a|
|Titan||1.4 x 1026||2.30||2.4 x 106 a|
|Triton||8.7 x 1025||2.00||1.6 x 106 a|
|Moon||7.4 x 1025||3.35||3.6 x 103|
|Callisto||9.7 x 1025||2.10||106 -- 105 a|
|Io||7.2 x 1025||4.00||106 -- 105 a|
|Europa||4.7 x 1025||3.80||106 -- 105 a|
r = ro(1 -- xrl),
|r[bar]c = ro (1-|| 3x |
For the initial mean density of protoplanets we may take the present mean density of Jupiter or of the Sun, because their relative mass loss cannot be very significant. For the Earth we take ro = 12 g cm-3, and it then follows that the initial radius was in the range 14 to 7.1 thousand kilometres, the loss of mass being anywhere between 2 to 3 and 0.2 times the present mass of the Earth. The loss of mass from Venus would be of the same order; much more mass could have been lost from Pluto -- if the high mean density for this planet is correct.
The total amount of material ejected from all the planets since the origin of the solar system could exceed 1029 to 1030 g. This value is of the same order as the total mass of comets and other minor bodies created during the history of the solar system. This shows that inside the planets there must have been powerful energy sources far greater than anything derived from gravitational collapse or radioactive decay. It is quite natural to suppose that the energy supply was preserved from the initial stellar condition of the planetary material.
The data from the system of asteroids agree well with our conclusions from the system of comets. Table II shows the distribution of the absolute magnitudes g of the 1746 permanently numbered objects. The first seven values, up to and including that for g = 10-11, probably characterise the real distribution of asteroidal sizes in the accessible region of space (up to 5.5 AU from the Sun), and from them we may obtain the following dependence of the number n and the mass M:
log M = 26.74 - 0.6 g.
Distribution of absolute magnitudes of minor planets
[*!* Image]Fig. 1. Distribution of absolute magnitude g of the minor planets. The broken line shows the distribution extrapolated from the brighter objects.
The extrapolated number of minor planets of g = 19.5 is thus n = 7.6 x 106, and their combined mass is M = 1019 - 1020 g, from which it follows that the total mass of the asteroids up to g = 19-20 is of the order 1026 to 1027 g. Considering that the total volume of the planetary system and the volume of the visibility region are in the ratio (40/5)3~500, we deduce that the total mass of asteroidal material in the solar system is some 1023 to 1029 g, which is again approximately consistent with the cometary data.
EVIDENCE FROM METEOROIDS
According to Brandt and Hodge (1964) some 107 to 109 g of meteoroidal matter encounter the Earth daily and are pulverised in its atmosphere. Taking into account the Earth's attraction, this corresponds to a volume of approximately 1015 km3. Supposing meteoroid density to be the same over the volume occupied by the system of planets (1030 km3) the total mass of meteoroids must amount to 1023 g. Since these particles move along the cometary orbits, orbiting the Sun in decades or at most a few centuries, we may deduce that the total amount of finely dispersed substance produced during the existence of the solar system cannot be less than 1023 x 106 to 7 = 1029 to 1030 g
Among photographic and radio meteors a significant proportion have small perihelion distances (q<0.4 AU) and large eccentricities; the majority have aphelion distances not exceeding 3 to 4 AU (Vsekhsvyatskii, 1967). More than a quarter of all the particles move in rather eccentric orbits relatively near the Sun. The Poynting Robertson effect implies that the lifetimes of such particles are rather small and measured only in hundreds or at most thousands of years. Solar corpuscular radiation is still more effective at dispersing and sweeping out these particles. We conclude that the particles observed near the Sun arise in the inner region of the solar system. It seems impossible to explain their character by capture from long-period orbits or their creation as a result of the disintegration of comets.
It has already been suggested that objects with orbits of small perihelion distance and small semimajor axis (e.g., P/Encke, P/WilsonHarrington, Icarus, the Apollo asteroids, etc.) could arise as a result of eruptive processes on Venus, the space missions having indicated temperatures there of the order 800 K, pressures of more than 100 atm, a large amount of dust in the upper atmosphere, and rapidly varying dark features above the cloud cover that appear to consist of clouds of volcanic ash.
The peculiarities of all the groups of minor bodies thus illustrate the rapid dynamical and physical evolution especially evident in the case of comets and meteoroids. Together with the results of analysis of meteorites they give evidence of the processes of ejection from the surfaces of satellites and planets (the Moon, the satellites of Jupiter and Saturn, Venus, Mars, and the Earth).
REFERENCESBrandt, J. and Hodge, P.: 1964, Solar System Astrophysics New York and London. Everhart, E.: 1969, Astron. J. 74, 735. Kuiper, G. P.: 1951, in J. A. Hynek (ed.), Astrophysics, McGraw-Hill, New York, Toronto and London, p. 400. NASA: 1969, Apollo 11: Prelimmary Science Report. Oort, J. J.: 1963, in The Moon, Meteorites and Comets, Vol. IV of the series: The Solar System (ed. by B. M. Middlehurst and G. P. Kuiper), University of Chicago Press, Chicago and London, p. 665. Sekanina, Z: 1966, Publ. Aston Inst Charles uruv. No. 48. Sekanina, Z.: 1968, Publ. Astron. InsL Charles Univ. No. 56. van Woerkom, A. J.: 1948, Bull. Astron. InsL Neth 10, 445. Vsekhsvyatskii, s. K.: 1962, PubL Astron. Soc. Pacific 74, 106. Vsekhsvvatskii, S. K.: 1966, Mem. Soc. Roy. Sci Liege Sez. 5 12, 469. Vsekhsvyatskii, S. K.: 1967, Priroda i Proisldlezhdenie Komet i Meteomogo Veshchesba, Prosveshchenie, Moscow. Vsekhsvyatskii, S. K.: 1971, Probl. Kosnich, Fiz. No. 6. wurm, K.: 1963, in The Moon, Meteontes and Comets, Vol. IV of the series: The Solar System (ed. by B. M. Middlehurst and G. P. Kuiper), University of Chicago Press, Chicago and London, p. 573.
The eruptive evolution process for the origin of comets, proposed by Prof. Vsekhsvyatskii, is quite distinct from the cometary-origin mechanism propounded by Immanuel Velikovsky (Cf. "The Birth of Venus from Jupiter," KRONOS, II, 1, pp. 3-5). Prof. Vsekhsvyatskii has, however, defended his own position with considerable vigour; and it is just possible that, sometime in the future, further scientific discovery may eventually support both hypotheses.
For now, it should prove highly instructive to list a few of the objections raised by some scientists against Prof. Vsekhsvyatskii's conclusions, along with the Soviet astronomer's rebuttal. The criticisms presented here were voiced at the June 1974 international symposium -- "Velikovsky and the Recent History of the Solar System" -- held at McMaster University in Hamilton, Ontario.
1) There is no basis for assuming that terrestrial volcanism could eject matter from Earth. This has never been observed.
This remark is the consequence of unfamiliarity with the history of volcanic phenomena on Earth - and with the conclusions of Lagrange, Humboldt, Cuvier, Pavlov, and other investigators. It reflects the mistaken notions of many contemporary geologists who consider volcanism only in terms of magmatic activity on Earth. Our analysis of the phenomena of powerful, explosive eruptions proved the expulsion of matter into interplanetary space even in the present period of relative tranquility on Earth (See Physical Journal, Kiev University, 1955, no. 8). Observations of the rings of Saturn, information about Venus during the history of the peoples of the Earth (1. Velikovsky), and many other data demonstrate the expulsion of matter from the surfaces of the planets. The results of molecular radiospectroscopy in the cosmos demonstrate the universality of this process in the universe.
2) There is no known mechanism by which matter could be ejected from Jupiter or Saturn or other planets.
The mechanism of eruptive evolution is delineated in my writings (See Ambartsumyan, Problems in Contemporary Cosmogony, 2nd edition, 1972). This problem still awaits detailed working out, following a clarification of the physical and dynamical principles of the internal structure of the planets consistent with the results of the "eruptive theory" Here are required radical changes in deeply rooted but certainly mistaken notions. The situation with this problem recalls the period between Copernicus' discovery and the subsequent completion of the Copemican revolution (Kepler, Galileo, Newton).
3) We have no hint of any "remnants of stellar sources of energy" in the planetary interiors, nor can it be imagined what kind of sources these might be.
This affirmation is completely unfounded The peculiarities of the giant planets, which have preserved high activity over 5 X 109 years; the condition of Venus, and also of all the other planets - long ago forced even many geologists to discard ideas about "zone melting" caused by aggregations of radioactive matter, and other similar hypotheses. True knowledge about the nature of the planets is still in its infancy, and it is necessary that a large number of scientists (not only astronomers, but also physicists, mechanicians, geophysicists, chemists, radio astronomers) acquaint themselves with the foundations of the "eruptive theory" Meanwhile, the discoveries of Pioneer 10 and Mariner 10 are important witnesses.
4) During expulsion from a planet, cometary ices would be vaporised; the comet would be dispersed, not congealed.
The answer to this question was already given by my work long ago. In the eruption of the icy envelopes of the planets (frozen atmospheres), icy masses (cometary nuclei) could not be subjected to noticeable vaporisation, even with the planets close to the Sun. Currently, this process of the disintegration of stellar substance in its planetary phase is studied by radio astronomers, who observe the sources of cometary molecules in the mm. and cm. ranges. I am turning my attention to the latest models for Jupiter's satellites (See Mercury, Vol. 3, No. 1, 1974), closely conforming to my own scheme for the evolution of the protoplanets.
The Soviet Venera 9 and 10 landings, and recent American radar studies of Venus (See Science News, 9/18/76, p. 181), have provided strong evidence of internal tectonic activity -- possibly volcanism -- on that planet. Additionally the postulated "greenhouse" effect for Venus' high surface temperature is totally incompatible with the latest astronomical findings for the planet. With respect to the Venusian data, it is especially appropriate to quote Prof. Vsekhsvyatskii once again: My work has proven that the upper atmosphere [of Venus], with its multilayered cloud cover saturated with aerosols (ashy or icy particles) will be completely opaque for solar rays in the optical range and that therefore the "greenhouse" model of Venus is groundless. A volcanic model of Venus was proposed in the collection, Problems of Cosmical Physics, No. 6, 1971, Kiev University.]