Solar system. The stars and the sources of their energy. Galaxy
The solar system is called the totality of the heavenly bodies moving around the Sun, which is a dynamic centre of this system. The solar system consists of the Sun and planetary systems, including all the natural space objects that revolve around the Sun. Turn around the Sun, 8 major planets with their satellites and rings: mercury, Venus, Earth, Jupiter, Saturn, Uranus, Neptune. They are divided into terrestrial planets similar to Earth, and giant planets similar to Jupiter. These groups are very different in their physical characteristics. To natural space objects in the solar system include dwarf planets and their satellites, and small bodies: asteroids, meteors and meteorites, comets, cosmic dust. Between the orbits of Mars and Jupiter lies the asteroid belt.
The age of the Solar system approximately 4.6 billion years.
The main features of the Solar system .
The planets move around the Sun in orbits close to circular ones. Comets also move in very elongated orbits, when moving near the Sun, the comet forms a tail.
The orbits of all planets lie nearly in the plane of the equator of the Sun.
The direction of revolution around the Sun of all the planets odinakovogo and coincides with the direction of rotation of the Sun. In the same direction as the spin of all planets except Venus and Uranus, and Uranus rotates almost “lying on side”
The mass of all the planets 750 times less than the mass of the Sun. The Sun’s mass is 99.8 % of the mass of the Sun C. S. holds its gravity planets and other Solar system bodies.
The terrestrial planets (located within the asteroid belt): less than giants on the weight and size, the slower the rotation. They have a large average density of matter. Three planets — Venus, Earth and Mars — there atmosphere. The atmosphere of Venus and of Mars consists of carbon dioxide. Only the Earth has a natural satellite, the Moon, and the Mars – Phobos and Deimos. Venus is the hottest planet of our system, its surface temperature is over 500 °C.
Giant planets (Jupiter, Saturn, Uranus, Neptune) beyond the asteroid belt: in tens or hundreds of times more massive than the terrestrial planets. Superior and size. Jupiter, for example, exceeds the Earth by volume 1320 times, and mass is 318 times. surrounded by a dense extended hydrogen-helium atmospheres containing small amounts of ammonia and methane. All giant planets low average density (large density of Neptune is 1.66 g/cm 2. the smallest of Saturn is 0.7 g/cm 2 ). They rotate very quickly around their axes (for Jupiter one turn in 10 hours). The giant planets are characterized by a large number of satellites and have rings, but only the ring system of Saturn is visible from Earth. Saturn has more satellites 62. Jupiter more massive than all other planets combined. The most distant planet from the Sun is Neptune.
The stars and the sources of their energy
In the sky (in one polusharii) we can see 2500 stars. The sun – our nearest star. Due to the proximity of the Earth to the Sun we have the opportunity to study the processes and generalize about similar processes in stars that are not visible due to their removal. The sun affects life on Earth. To judge the temperature of the Sun (and stars) on it (them) radiation. The surface temperature of the Sun T=6000 0 K. It is a source of radiation of different wavelengths – from radio to x-ray and gamma radiation.
Stars — glowing balls of gas, different color, mass, luminosity and radius. Stars according to their spectra and color are divided into spectral classes: M(cu)-3000 To 0, G(yellow)-6000 To 0, A(Bel)-10000 To 0, and B(blue). The sun is called a yellow dwarf because of the color and radius. The stars (they are marked on the diagram “spectrum — luminosity”)are divided into groups: red giants, supergiants, white
The energy source of the Sun and stars of the main sequence are fusion reactions of helium synthesis from hydrogen. The sun is 70% hydrogen. The reactions take place in the center, in the core of the star at temperatures above 10 6 K.
Observation found that all the stars form a huge star system — Galaxy (from the Greek word Galacticos — dairy). The milky Way – our Galaxy is a giant spiral galaxy filled with star clusters, gas and dust. The solar system is in it. In the Galaxy of about 100 billion stars! The average distance between stars in the Galaxy is 5 light-years. The galaxy rotates. The sun, at a distance of 26,000 light-years from the galactic center, is drawn at a speed of 220 km/h around the Galaxy. Gas and dust obscure from us the center of the milky Way galaxy where a massive black hole.
Along with spiral galaxies there are elliptical and irregular galaxies . Elliptical galaxies do not rotate, they lack the gas and dust. They consist mainly of old stars.