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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
Some comets, rotating now in the Solar system, were originally in other star systems and ended up here due to the fact that the Sun is their “kidnapped”.
To this conclusion came a group of astronomers from the North-West research Institute in USA.
“If the results of our models and calculations are correct, then many comets that are present now on the outskirts of the Solar system originally was not here,” says scientific specialist of the Institute’s Hal Levison.
From his point of view, a significant proportion of comets that are now in the zone of the Solar system known as the Oort Cloud is aliens from other star systems.
“We know that stars are formed in clusters. Sun was born inside a huge community of other stars that were formed from a single cloud of gas and dust. In this cluster the stars were so close to each other that were able to “steal” different objects, such as comets through its gravity,” he says. Continue reading
Space when observed with the naked eye
Comets and meteors
Unlike stars and planets that the naked eye perceives as a luminous point, the comet is observed in the form of an elongated spot, in which through careful observation can see the relatively bright concentration – “head” and a conical “tail”. With the aid of the telescope each year find 5-10 comets, but rarely any of them are so bright that accessible to observation with the naked eye. Like planets, comets move around the Sun. But unlike the planetary orbits of the trajectory of comets typically have very elongated. The periods of revolution around the Sun fills the interval from a few years (comet Encke is for 3.28 years) to several thousand years (comet Hale-BOPP – 3000 years).
The comet nucleus, from which emerge jets of gas, plasma and dust all the more intense, the closer to the perfect Sun the comet is a huge (from kilometers to tens of kilometers in diameter) snowball. It is composed of molecules containing hydrogen, oxygen (e.g., H 2 O), carbon and nitrogen, as well as from dust, which escapes as ice sublimation (i.e., in the transition to the gaseous state under the action of radiation of the Sun). In the core there are larger solid particles. Continue reading