The origin of the solar system
The sun and the solar system was formed about 4.5 billion years ago. The solar system originated from a cloud, composed of gas and dust particles moving. Under the influence of its weight of it formed a disk in the center of which formed the Sun .
Gradually within the disk began to form solid materials. They faced each other, whereby a large celestial body. Their size corresponds to the existing planets. Inside the nebulae, where the temperature was high enough to form rocky planets. Far from the center formed the giant planets, they contain a large amount of ice, and they were surrounded by a thick layer of gas.
Within the Solar system the temperature even higher, and planets formed from rocky debris of the solar nebula. They are in contact with each other, forming a large celestial body. They attract each other by virtue of the power of the law of gravity and give birth to planets of terrestrial group. The atmosphere of the Earth and Venus, the largest among them, tight.
The atmosphere of Mars, a smaller planet is less dense, and mercury. the smallest planet of this group, it is very sparse compared to earth is not readily available.
Outside the Solar system,on the contrary, or due to the large number of large heavenly bodies, or because of the excess water formed a huge body, surrounded by natural satellites. Their weight is about ten times the mass of the Earth, and the gravitational force is so great that it is able to support a thick atmosphere and to attract the gaseous part of the nebula (around the Solar system at the dawn of its appearance.) Here are formed gaseous giant planets.
The asteroids arose from the slightest rocky debris formed within the Solar system in the initial period of its existence. They are mainly located between the orbits of Mars and Jupiter. The largest of the asteroids referred to as minor planets (they are called), the rest can be considered as objects that are little more than large stones of the wrong form.
The first asteroid, Ceres, was discovered in 1801 by Italian astronomer Giuseppe Piazzi. The diameter of Ceres is about 1000 km, the total Length is somewhat greater than this figure. It is estimated that the total mass of the asteroid is less than 1/1000 the mass of Earth.
In 1993 the space Shuttle “Galileo” transmitted to earth Photographs taken in the vicinity of two asteroids – Gaspra and IDA. They are irregular in shape, their surface pitted with craters. Length IDA is only 55km, but this asteroid has a small companion – Atilla. Its diameter is about 1.5 km away.
The composition of asteroids is not the same. The surface 75% of asteroids are dark, non-shiny, but there are asteroids, composed of greyish rock formations or having a metallic luster.
Comets are the most beautiful body in the Solar system. Some of them are connected to the Sun forces of attraction. They move around on elongated elliptical orbits of different sizes and are available periodically as the famous Halley’s comet. She returns to the Sun at intervals of about 76 years and rotates between the Solar system and a space located beyond the orbit of Neptune.
There is a hypothesis according to which most of the comets originated beyond the orbit of Pluto, where there are many chunks of ice remaining after the formation of the Solar system. It is believed that in this region, called the Oort nebula by the name of the astronomer, who put forward this hypothesis, there are about 100 billions of comet nuclei. They can be seen only during periods of gravity in the Solar system.
The core of “dirty snow”
The comet nucleus was described by the astronomer Fred Wippler. He represented it as a “ball of dirty ice”, as the core consists of a mixture of ice and rocky dust and substances.
When the comet approaches the Sun, its heat causes evaporation of the liquid from the ice. The core, the diameter of which is several kilometers, is covered with the gas, forming a comet tail that stretches for thousands of kilometers. Reflecting off of the tail light of the sun makes the comet visible. Typically, the mass of the comet is one-billionth of the mass of the Earth.
Every year astronomers see an average of 20 comets. Some of them are new, that is before them is not fixed, and some so-called periodic, that is, they appear after a certain number of years. Very rarely a comet begins to glow, and then it can be seen to the naked eye.