Physical nature of comets
A small nucleus a few kilometers in diameter is the only solid part of the comet, and it focuses almost all of its mass. The mass of comets is very small and does not affect the motion of the planets. Planets also produce large perturbations of the comets. The nucleus of the comet, apparently, consists of a mixture of dust, solid matter pieces, and frozen gases such as carbon dioxide, ammonia, methane. When approaching such a kernel to the Sun gases evaporate and create a flying who — gas shell. The great comet shell is not round, but has a parabolic shape — the head, which passes into the tail.
The closer the Sun approaches the comet, the brighter and the longer its tail. The comet’s tail sometimes reaches a length of the distance from the earth to the Sun, and the head of the comet is the size of the Sun. With the removal of the Sun from view and the brightness of comets are changed in reverse order and the comet disappears from view, reaching the orbit of Jupiter. Gases and dust emitted from the nucleus in the head of the comet, repel the pressure of sunlight and corpuscular flows away from the Sun and creating a comet tail. Most often it is straight, thin, scaly. Range of the head and tail of a comet usually has a bright band. Spectrum analysis shows that the head of a comet consists mostly of vapour of carbon and CYANOGEN, and its tail has ionizirovannykh carbon monoxide (carbon monoxide). The spectrum of the comet’s nucleus is a copy of the solar spectrum, that is, the core glows with reflected sunlight. Coma, head and tail also glow with a cold light, absorbing and then perezluha solar energy (this kind of fluorescence). On the distance of the Earth from the Sun the comet is hotter than the Earth. The large and bright comets sometimes a wide, curved tail fan.
An outstanding Russian scientist F. A. Bredikhin developed a method for determining the curvature of the tail magnitude of the repulsive force of the Sun. He established the classification of comet tails and explained in a number of observed phenomena in them by the laws of mechanics and physics. In recent years it has become clear that the movement of the gases in the straight tails and kinks in them due to the interaction of ionized molecules of gases such tail hits them with a stream of corpuscles in the solar wind. These flows carry magnetic field. Ions can’t move across its lines of force, magnetic field and discards ions in the gas tail of a comet. In such cases, a repulsive force of the solar wind exceeds attraction to the Sun thousands of times. This is one of the brightest examples of the struggle of opposites in nature. Flash hot gases on the Sun are accompanied by increased short-wave radiation and the solar wind. It causes a sudden flash of brightness of comets.
In 1910 the Earth passed through the tail of Halley’s comet. Although the comet tail has carbon monoxide, it is so attenuated that no tests failed to detect the impurity in the air. Gases even in the head of the comet is extremely sparse. The collision of Earth with a comet extremely unlikely event. If it happens, the Earth is in no way threatened. In fact, heating up in the air, the ice core will evaporate, and released upon evaporation of the solid particles will cause the phenomenon of rain “falling stars”, or meteors.