the Universe is everything that exists: a matter, space, energy and time. All stars, planets and other space bodies enter into it.
The Universe is so huge that its sizes cannot be realised. That part of the Universe which we see, reaches 1,6 million million million million in km, - and is conducted to nobody, how much it is great outside of the visible.
Many theories try to explain, from what there was a Universe and as it has taken the today's form. According to the most widespread, the Universe was born as a result of huge explosion about 15 thousand million years ago. Thereof phenomenal explosion has arisen not only a matter, but also energy, and space, and even time! To say that was to so-called "сюыі°юую тчЁ№тр" it is senseless: to "сюыі°юую тчЁ№тр" there was nothing!
Astronomers believe that after the big explosion the Universe was improbably heated and full of radiation. Approximately in 10 seconds nuclear particles - protons, neutrons and elektrony were generated. Atoms - atoms of hydrogen and helium - were formed some hundreds thousand years later when the Universe has considerably extended in sizes and has cooled down.
Echoes of the big explosion
If the big explosion has occurred 15 thousand million years ago, the Universe should grow cold by this time to temperature about three degrees on Calvin's scale, that is three degrees above absolute zero. Using radio telescopes, scientific have registered the background radio noise corresponding to this temperature on all star sky, and consider them till now as echoes of the big explosion reaching us.
According to one of the most popular scientific legends, Isaak Newton has seen, how the apple has fallen to the ground, and has understood that it happens under the influence of the force proceeding from the Earth, - a gravity. Really, each body in the Universe has own gravity. The size of this force depends on weight of a body. The apple has small weight and its gravity does not influence movement of our planet. The Earth has the big weight and draws an apple to itself.
Forces of an attraction keep all heavenly bodies in their space orbits. The moon moves on an orbit of the Earth, instead of keeps away from it. Force of an attraction of the Sun keeps in circumsolar orbits of a planet, and force, much more big gravitational force of the Sun, keeps our star in its position in relation to other stars.
Our Sun - a star, and usual enough and the most average sizes. As well as all other stars, the Sun are represented by a sphere from shone gas and like the enormous furnace allocating light, heat and other forms of energy. The sun and planets in its orbit form Solar system. Other stars in the sky seem tiny, but it because they are very far from us: actually some of them in diameter in hundreds, time exceeds our Sun!
Stars and galaxies
Astronomers define a site of stars, having them in constellations or in relation to them. The constellation is a group of stars, visible on a certain site of the night sky and actually not always being nearby.
In boundless space open spaces of a star are grouped in the star archipelagoes called by galaxies. Our Sun and its planets enter into our Galaxy which is called as the Milky Way. The Milky Way - it is far not the greatest galaxy, but it is so huge what to present it hardly probably.
Distances are measured in the Universe in relation to a velocity of light, faster which the mankind does not know anything. The velocity of light is equal to 300 thousand in km/s. Astronomers use such unit, as light year: this distance which the ray of light would take place for a year, that is 9,46 million million in km! The star nearest to us - Proxima - is in constellation of the Centaur on a distance of 4,3 light years. Looking at this star, we see its such what it was more four years ago. And light of our Sun reaches us for 8 minutes and 20 seconds!
The Milky Way, from its hundreds thousand millions stars, has the form of a huge rotating wheel with acting axis - a nave. The sun is located more close to a rim of this wheel, in 250 thousand light years from its axis. The sun turns around on the orbit round the Galaxy center for 250 million years.
Our Galaxy - only one of many, and how many their everything, does not know anybody. Are already opened more than billion galaxies. In each of them - many millions stars. Farthest of already known galaxies are in hundreds millions light years from earth dwellers, hence, studying them, we peer into the most remote past of the Universe. All galaxies leave from us and from each other, seemingly, that the Universe still extends and that scientists have knowingly come to a conclusion about the big explosion as it pervonachale.
What there are stars?
Stars happen different, but all of them have once arisen also all through millions years will disappear. To our Sun almost 5 billion years and, by estimates of astronomers, it will exist as much again, and then will start to die. The sun - the unary star, many other stars are binary, i.e., As a matter of fact, consist of two stars rotating around each other. To astronomers the threefold and so-called multiple stars consisting of many star bodies also are known. The largest stars are called as supergiants. To them Antares, its diameter in 350 times more diameter of the Sun belongs. However, all supergiants have very small density. - giants - have less large stars diameters in 10-100 times more solar, their density too is small, but more than at supergiants. The majority of visible stars, including the Sun, average stars are classified as a star of the main sequence, or. Their diameter can be both ten times more, and ten times there is less than diameter of the Sun.
The smallest stars of the main sequence are called as red dwarfs, and still the smaller bodies which not so are not concerning stars the main sequence, - white dwarfs. White dwarfs (the sizes about our Earth) are very dim, but are excessively dense: their density above water density in 100 thousand-20 million times. Only in the Milky Way of white dwarfs can be to 5 billion though till now scientists have opened some hundreds such bodies.
a star Life
Each star is born from a hydrogen and dust cloud. The Universe is full of such clouds. Star formation begins, when under the influence of any (still nobody understood) forces and under the influence of gravitation occurs, as astronomers tell, a collapse, or compression of a heavenly body: the cloud starts to rotate, and its center heats up. When the temperature in a star cloud reaches many millions degrees, nuclear reactions in which course of a kernel of atoms of hydrogen incorporate begin and form helium. Energy made by reactions is liberated in the form of heat and light, and the new star lights up.
Round new stars residual gases and a star dust are observed. Planets are formed of this matter.
The Destiny of a star in many respects depends on its weight. When the star like our Sun uses all hydrogen "=юяыштю" it gelievaja the cover is compressed, and external layers extend. At this stage of the existence the star becomes the red giant. In due course its external layers sharply depart, reserving a small bright kernel of a star - the white dwarf. Gradually the star will be cooled, having turned to the black dwarf, - huge weight from carbon.
The Stars which weight several times exceeds weight of the Earth, the drama destiny expects. In process of an exhaustion of their nuclear fuel they extend and turn in supergiants which are much larger than red giants. Then, under the influence of gravitation, there is a sharp compression of their kernels. The liberated energy unimaginable explosion carries a star on pieces. Such explosion astronomers name a birth supernew. Any time the supernew shines in millions times more brightly the Sun. After a supernew star depending on initial weight there can be the small body named a neutron star. Such star with a diameter no more than several tens kilometres consists of firm neutrons, paternal its density many times over exceeds huge density of white dwarfs.
In some supernew force of a collapse of a kernel is so great that matter compression practically leads to its disappearance. Instead of a matter there is a site of a space with improbably high gravitation - a black hole. Owing to the nature black holes cannot be visible, nevertheless, astronomers have established their site.
The Universe also conceals in itself mysterious formations - quasars. Probably, it is brightly shone kernels of far galaxies. Pulsars - the formations which are regularly letting out bunches of energy are not less mysterious. According to scientists, they are quickly rotating stars from which light beams proceed.