Celestial bodies and the solar system

The house in which we live is our solar system. It is not yet known whether we are alone in the universe. Celestial bodies are scattered all over the Cosmos, and life may well exist in other manifestations not only on Earth. Solar heat gives birth to life on our planet, since the Sun is our only star.

The heavenly bodies of our system

The sun is the center of our system. The motion of celestial bodies is carried out around the Sun in separate orbits. On the planets, thermonuclear reactions do not flow. The sun, thanks to the reactions, heats the planets that revolve around it. All planets are large and have a spherical shape, which they acquired as a result of evolution.

Previously, astrologers assumed that there are only seven planets in the solar system. These are the Sun, the Moon, Mercury, Venus, Mars, Jupiter and Saturn.

Very long time, before the discovery of the solar system, people believed that the Earth is the center of everything and all the cosmic celestial bodies, including the Sun, move around it. Such a system was called geocentric.

In the 16th century, Nicholas Copernicus proposed a new system for building the world, called the heliocentric system. Copernicus stated that in the center of the world is the Sun, not the Earth. The change of day and night is due to the rotation of our planet around its own axis.

Other Solar Systems

The invention of the telescope allowed people to see for the first time that comets moving in the sky are approaching the Earth, and then they leave it. After almost 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 was followed when the existence of the satellites of Jupiter was discovered.

Are there other planetary systems from other stars? Absolutely, this is not yet known, but their existence can not be doubted.

In 1781, the discovery of the planet Uranus, large and far from the Earth, followed. The planets turned out to be not seven, and the system of the cosmic hierarchy was revised.

For a long time there was an opinion that the disintegration or formation of a planet between Mars and Jupiter gave rise to all asteroids. To date, scientists have more than 15,000 asteroids.

In recent years, heavenly bodies have been discovered, which it is difficult to attribute to a certain class, comets or planets. In these objects, the orbits are very elongated, but there are no signs of activity of the tail and comet.

Two kinds of planets

The planets of our system are classified into giants and terrestrial groups. The difference between the terrestrial planets is a large average density and a hard surface. Mercury, in comparison with other planets, the density is greater due to the core of iron, which is 60% of the mass of the entire planet. Similar to the Earth in mass and density, Venus.

Earth differs from other planets by the rather complex structure of the mantle, whose depth is 2900 km. Under it is a nucleus, presumably metallic. Mars has a relatively small density, and the mass of its core is not more than 20%.

Celestial bodies belonging to the group of giant planets have low density and complex atmospheric chemical composition. These planets consist of gas and their chemical composition is close to solar (hydrogen and helium).

Scientists agreed to regard the planet as heavenly bodies circling around the Sun-star, possessing a strong gravitational attraction, a spherical shape and occupying a separate orbit.