Abstract
MECHANICAL THEORY OF COMETS.—Prof. J. M. Schaeberle, in the Astronomical Journal, No. 306, communicates a “preliminary note on a mechanical theory of comets,” this being “a strictly logical consequence of the mechanical theory of the corona.” The principles which serve as a basis maybe said very briefly to be the following. Any given solar eruption gives rise to both prominences and streams. The ejective force being the same, the mass of a given volume of coronal stream is less than that of a prominence. Assuming mean density of coronal stream to be one-seventh of that of accompanying prominence, the same explosive force which during the last eclipse sent prominences to a height of 80,000 miles, will send coronal matter forming the streams to an infinite distance. Coronal streams extend far, then, into space. The densest portion of the stream is located at the point of minimum velocity, and the coronal streams visible in the last total eclipse were, Prof. Schaeberle says, according to his photographs, apparently most dense in the higher regions, proving that the matter was in rapid movement. The mechanical theory of comets supposes coronal streams to issue from the sun at all angles. These streams will penetrate far into space (some crossing one another). The atmosphere of a comet on striking these streams will in projection be in the form of luminous, nearly concentric, arcs, the greatest brilliancy being near the most advanced part of each stratum. More than one coronal stream will produce in the comet multiple tails, the angles between the tails being a function of the velocities of motion, and the inclinations of the streams. An examination of the cases where a tail is turned towards the sun is explained by a coronal stream, having a less velocity than that of the receding comet, thus producing such a phenomenon the moment the stream is entered. Prof. Schaeberle, at the conclusion of the papers, refers to a satisfactory explanation of the “Gegenschein,” and also to a plausible explanation of the Aurora, both based, on the coronal streams.
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Our Astronomical Column. Nature 49, 84–85 (1893). https://doi.org/10.1038/049084a0
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DOI: https://doi.org/10.1038/049084a0