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
Solar system – 8 planets and over 63 of the satellite, which are opened more often, several dozen comets and many asteroids. All cosmic bodies move in their precise directional trajectories around the Sun, which is 1000 times harder than any body in the solar system combined. The center of the solar system is the Sun – the star around which orbits the turning of the planet. They do not emit heat and not light, but only reflect the light of the Sun. In the solar system now officially recognized as the 8 planets. Briefly, in order of distance from the sun, we list them all. And now a few definitions.
A planet is a celestial body that must satisfy four conditions:
1. the body must revolve around the star (for example, around the Sun);
2. the body must have sufficient gravity to have a spherical or similar shape;
3. the body should not be near its orbit of other large bodies; 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