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
So far the only scientifically proven the possibility of interstellar travel is the acceleration of the spacecraft up to relativistic speeds (punctures and convolution space still remain purely speculative projects). The ship may abandon astronauts in suspended animation for a dozen or even a hundred light years and return them to Earth. But because of the relativistic slowing of Board time on earth will pass away not even the century and Millennium — and it is somehow not pleasing. In addition to other galaxies to get to, there’s no cryostasis will not help. But it is possible that the output is still there.
For 15 years Professor of theoretical physics at Imperial College London, Joao Magueijo develops the hypothesis of variable speed of light (Varying Speed of Light, VSL). However, he minded very little, since most scientists believe this idea is pure nonsense. But we are talking about science impossible, so will try to temper my skepticism.
VSL-models calculated in several ways. They all say that measured on Earth the speed of light in a vacuum is not an absolute constant, and only the lower limit of the speed of propagation of electromagnetic waves. In certain (frankly, vesimaailma) conditions may be many times 299 792 km/s. 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