The world of the unknown - Onua.org

Halley's comet - In 1705 Edmond Halley, using Newton's laws of motion, predicted that the comet, which was observed in 1531, 1607 and 1682 years, should return in 1758 (which, alas, was after his death). Comet really returned, as was predicted, and was later named in his honor.

The problem comet hazard analyzed in detail in numerous publications. It should be noted that the greatest danger is a massive long-period comets, their appearance is often unexpected, because of arbitrary orientation of the planes of the orbits and large or very large orbital period. Moreover, many of these comets is aperiodic, i.e move in non-closed trajectories (parabolic or hyperbolic) and therefore are really new. These comets possible over a high speed collision with the Ground - up to 72 km/s (on a collision trajectory)that could lead to a global disaster. The possibility of such catastrophic events is proved by many facts.

In the Solar system besides the large and small planets there are other heavenly bodies. First of all, it comets, which is also called the caudate stars. Is small, the size of several kilometers, blocks of stone and ice. According to the laws of Kepler's comet, like the other bodies of the Solar system, moving in elliptic orbits. But their orbits are very stretched, so that the most remote from the Sun point is usually far beyond the orbits of the most distant planet Pluto.

About seven thousand years ago in a remote corner of outer space suddenly exploded star, throwing off the outer layers of matter. Relatively large and massive star is suddenly faced with a serious energy problem - its physical integrity was under threat. When was passed stability boundary, broke into a fascinating, highly powerful, one of the most disastrous in the Universe explosions that produced a supernova. Six thousand years raced on the expanses of space light from this star in the constellation of Taurus and finally reached the Earth.

Space is often called the airless space, believing it empty. However, it is not. In interstellar space is dust and gas (mostly helium and hydrogen, the latter much more). In the Universe there are whole cloud of dust and gas. These clouds we do not see the center of our Galaxy. Of these clouds can have dimensions in hundreds of light years, and part of them can be compressed under the influence of gravitational forces.

In the 60-ies of XX century by accident when monitoring radio telescope, which was designed to explore flickers of cosmic radio sources, Jocelyn bell, Antony hewish and other employees of the University of Cambridge in the UK found a series of periodic pulses with a duration of 0.3 seconds at a frequency of 81.5 MHz, which was repeated surprisingly constant time, through 1,3373011 seconds. It was very unlike the usual chaotic random picture occasional flickers. There was even an assumption about extraterrestrials, who at the Land of their signals.

Why the starry sky as if spinning and why polar star almost motionless? It turns out that the reason for this apparent motion of the stars is in the rotation of the Earth. Just as man, swirling around the room, it seems like the whole room is spinning around it, and we are located on the rotating Earth, we see, as if moving stars.

A star is born lasts millions of years, and is hidden from us in the depths of dark clouds, so the process is virtually inaccessible to direct observation. Astrophysicists are trying to explore it in theory, with the help of computer simulation. Turning a fragment of clouds in the star accompanied by gigantic change in the physical conditions: the temperature of the substance increases by approximately 106 times, and the density - 1020 times. Tremendous changes all the characteristics of the emerging stars are the main difficulty theoretical consideration of its evolution. At the stage of such changes, the original object is not a cloud, but not a star. Therefore, it is called a protostar (from the Greek. "protos" - "first").

Stars whose mass is 1.5-3 times more than the Sun will not be able in the end to stop his grip on the stage of the white dwarf. Powerful gravitational force will shrink them to the density at which happens "neutralization" substances: interaction of electrons and protons will lead to the fact that almost all mass stars will be enclosed in a neutron. Formed neutron star. The most massive stars can contact neutron, after they explode as supernovae.

Molecular clouds, these "factory of stars", produce the stars of various types. The mass range of newborn stars extends from a few hundredths to 100 Solar masses, with little stars formed much more frequently than larger ones. On average in the Galaxy are born annually about a dozen stars with a total mass of about five Solar masses.

Even Herschel discovered on the background of the milky Way dark failures, which he called "holes in heaven". At the end of the XIX century on Litskai Observatory (USA) astronomer Edward Bar-backgammon began systematic sky photography. By 1913 he found about 200 dark nebulae. In his opinion, they were clouds absorbing light matter, and not the spaces between the stars, as did Herschel.

Stars of the greater mass of end their life otherwise. Helium nucleus of such stars, compressed, heated. It begins synthesis of carbon, forming carbon core. It also shrinks begins, the larger heating, synthesis of oxygen, etc. In the end, the star begins to resemble a bulb in the middle of which, at the last stage of the chain reactions Matures iron-Nickel core, in which no reaction to go can't do it anymore, that is formed white dwarf.

How are stars such as the Sun? What are the fundamental processes responsible for what dark diffuse interstellar cloud composed of gas and dust, it becomes much more dense luminous object? Astronomers from the United States and the European southern Observatory has made an important step on the way to understanding this fundamental question of astronomy. They undertook a detailed examination of the inner structure of small interstellar cloud known as Barnard 68 (B68).

After "burnout" thermonuclear fuel in the star, the mass of which is comparable to the mass of the Sun, in the Central part of the kernel density of matter becomes so high that gas properties change drastically. This gas is called degenerate, and the stars, he composed, - degenerate stars.

Looking at the starry sky, you can see that stars differ in their brightness, or as they say astronomers, in its apparent brightness.