The structure of the comet hypothesis of the origin of comets
The dust and ion tails of comet Hale-BOPP
But, in spite of research that freedom from prejudice was very slow: for example, Louis XIV was afraid of the comet of 1680 year, because it’s considered a portent of his death. The greatest contribution to the study of the true nature of comets was made by Edmond Halley. His main discovery was the establishment of the frequency of appearance of the same comet in 1531, 1607, 1682 Passionate about astronomical research, Halley became interested in the movement of the 1682 comet and calculate its orbit. He was interested in the path of its movement, and since Newton had already conducted similar calculations, Halley turned to him. The scientist immediately gave the answer: the comet will move in an elliptical orbit. At the request of Halley Newton presented his calculations and theorems in the treatise “De Motu”, that is “On the move”. Having the assistance of a Newton, he was engaged in calculation of cometary orbits by astronomical observations. He managed to collect information about the 24 comets. Thus appeared the first catalog of cometary orbits. In its catalog Halley found that three comets are very similar in their characteristics, from which he concluded that it’s not three different comets, and the periodic appearance of the same comet. The period of its occurrence was equal to 75.5 years. She was subsequently named Halley’s comet. After the catalog Halley appeared a few directories where we register all poyavivshiesya in the distant past, and currently the comet. The most famous of them: the bald and Obaldia, and first published in 1972, the catalogue of Marsden’s considered most accurate and reliable.
The nature of comets, their birth and death
Some cometary nuclei have retained relict ice below loose layer of insulating refractory components, and still in the asteroid belt sometimes reveal short-period comets moving in nearly circular orbits. An example of such a comet may be comet Smirnova – Chernykh, opened in 1975. Currently it is generally accepted the hypothesis of gravitational condensation of all bodies in the Solar system from the primary gas-dust cloud that had similar solar chemical composition. In the cold zone of the cloud had condensed the giant planets: Jupiter, Saturn, Uranus, Neptune. They absorbed the most abundant elements of the protoplanetary cloud, resulting in their mass increased so much that they were capturing not only solid particles, but also gases. In this same cold zone was formed and the icy nuclei of comets, which went partly on the formation of giant planets, and partially, the growth of the masses of these planets, they were discarded to the periphery of the Solar system, where he formed a “reservoir” of comets – the Oort cloud. As a result of studying the elements of nearly parabolic cometary orbits, as well as the use of methods of celestial mechanics has been proven that the Oort cloud really exists and is quite stable: the half-life is about one billion years. The cloud is constantly updated from different sources, so it does not cease to exist. F. Whipple believes that in the Solar system beyond the Oort cloud exists and a closer region, densely populated by comets. It is located beyond the orbit of Neptune, contains about 10 comets and it is the prominent perturbations in the motion of Neptune, which were previously attributed to Pluto, has a mass two orders of magnitude greater than the mass of Pluto. This belt could be formed as a result of the so-called “diffusion of cometary orbits”, a theory which was most fully developed by Riga astronomer K. Stancom. It is a very slow accumulation of small planetary perturbations, which becomes a gradual decrease of the semimajor axis of the elliptic orbit of the comet.
Gas-ion tail comet Machholz