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. Continue reading
Unlike planets, comets move on highly elongated orbits, and therefore are visible only at short periods close to the Sun.
The main part of any comet is its nucleus .
According to the hypothesis of the famous American researcher of comets Fred Lawrence Whipple, cometary nucleus is an ice consisting of a mixture of frozen water and frozen gases interspersed with refractory rocky and metallic particles . Figuratively speaking, it looks like a “dirty iceberg”.
Let us imagine that we see the newly opened the comet, which is somewhere in the vicinity of Jupiter’s orbit. Seeing through the telescope hazy pale speck, like a spherical nebula (such unattractive are presented to the observer of a distant comet), we may be disappointed at first. With the approach of the comet to the Sun the solar flux increases. Comet “ice” begin to evaporate rapidly. Around the nucleus formed a vast glowing gas shell – coma. Together with the core of it is the head of the comet. Continue reading
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Inside the comet 67P/Churyumov — Gerasimenko there are no large voids. The mission of “Rosetta” the European space Agency made measurements that clearly demonstrated and solved the old mystery. Comets are icy debris left over from the formation of the planets 4.6 billion years ago. Spacecraft have visited a total of eight comets, and through these missions we pulled a picture of the basic properties of these space-time capsules. On some questions the answers were found, others appeared.
Comets, as we know, consist of a mixture of ice and dust, and if there were compact, gravity superior to water. However, previous measurements have shown that some of them have very low density, much lower than water ice. Low density means that the comet must be extremely porous.
But what is this porosity: due to large voids in the subsurface of the comet, or due to a more homogeneous structure with low density? Continue reading