house in which we live - that is our solar system.It is still unknown, are we alone in the universe.The celestial bodies are scattered throughout the cosmos and life may exist in the other its manifestations, not only on Earth.Solar heat creates life on our planet, as the sun - our only star.
heavenly bodies of our system
sun - the center of our system.The movement of the heavenly bodies is carried around the Sun on specific orbits.On planets thermonuclear reactions do not occur.Sun, thanks to reactions heats the planet, which rotates around it.All the planets are large and have a spherical shape, which they acquired as a result of evolution.
Previously, astronomers assumed that there are only seven planets in the solar system.This - Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn.
A long time ago, before the discovery of the solar system, people believed that the Earth - the center of everything and all the cosmic celestial bodies, including the sun, move around it.Such a system was called geocentric.
In the XVI century, Nicolaus Copernicus proposed a new system of construction of the world, called the heliocentric.Copernicus said that the world is located in the center of the Sun, not the Earth.Change the day and night is due to the rotation of the planet around its own axis.
other solar systems
invention of the telescope for the first time allowed people to see that in the sky moving comets that come close to Earth, and then leave it.After nearly 20 centuries, scientists have determined that the cosmic celestial bodies are able to rotate not only in orbit around the Earth or the sun.This conclusion followed when discovered the existence of Jupiter's moons.
Are there other planets around other stars?Absolutely it is not yet known, but their existence can be no doubt.
In 1781 followed the opening of a large and distant from the Earth planet Uranus, ieThe planet was not seven, and the system was revised cosmic hierarchy.
For a long time it was believed that the collapse or the formation of a planet between Mars and Jupiter has created all the asteroids.Today scientists has more than 15,000 asteroids.
in recent years have opened the heavenly bodies, which are attributed to any particular class, comets or planets, it is difficult.These objects are very elongated orbit, but there are no signs of activity, and the tail of a comet.
Two kinds of planets
planets of our system are classified into giants and terrestrial.The difference between the group of planets Earth - more than the average density and solid surface.Mercury has in comparison with other planets, greater density due to a core of iron, which is 60% of the mass of the planet.Similar to Earth in mass and density of Venus.
Earth different from other planets rather complex structure of the mantle, the depth of which is 2900 km.Under it is the nucleus, presumably a metal.Mars has a relatively low density and mass of its core is not more than 20%.
heavenly bodies belonging to the group of giant planets have low density and complex atmospheric chemical composition.These planets consist of gas and its chemical composition is close to sunlight (hydrogen and helium).
Scientists have agreed to consider the planet celestial bodies orbiting the stars, the sun, have a strong gravitational pull, spherical and occupies a single orbit.
