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What celestial bodies have tails?

These "tails" inhabitants of the Solar system - comets. The name of the comet in Greek means "hairy", "shaggy". In ancient Greece, and later in the middle ages, comets usually portrayed as the severed head with flowing hair.

The comet Ikeya-janga
The Comet Ikeya-Jhang.
She was seen in March 2002. Famous, in particular, the fact that was visible in the sky near the famous galaxy of the Andromeda Nebula.

Comet is formless cosmic bodies in the Solar system. They move in a highly elongated elliptical orbits. Many comets period of circulation is very large by human standards, and is more than 200 years. Such comets are called long-period. Comets with periods less than 200 years is called short Cycling. Currently there are several dozen long-period and more than 400 short-period comets.

The orbit of Halley's comet
The comet's orbit compared to the orbits of the planets

The orbit of the comet

These space objects have negligible mass and distance from the Sun does not detect. Comets consist of stone or metal core encased in an icy shell of frozen gases (carbon dioxide, ammonia). As it approaches the Sun, the comet starts to evaporate, forming a "who" - the cloud of dust and gas surrounding the nucleus. Moreover, these substances comets pass into the gaseous state directly from solid, bypassing the liquid - this phase transition is called sublimation. The nucleus and the coma to form the head of the planet. As it approaches the Sun the gas cloud forms a huge gas plume - tail length in tens or even hundreds of millions of kilometers.

Coming from Sun light rays and the flow of electrical particles deflect the comet tails in the direction opposite to the light side. The same solar wind causes the illumination of the rarefied gas in the tails of comets.

The structure of the comet
Part of the comet
Note the two tail - dust and plasma

The bulk of the comet is concentrated in its nucleus, but 99.9% of the light radiation coming from the tail, because the core is very compact, but also has a low reflection coefficient.

Large comet may be visible for several weeks. Having flown about the Sun, they are deleted and disappear from sight. Many comets have been observed regularly.

The comet Ikeya-janga
Comet Maketa.
This comet became a real sensation in January 2007. Bright, with a huge fan-shaped tail, it does not leave indifferent those who were lucky enough to see her. But in all its glory comet Maketa was observed only in the southern hemisphere of the planet.

Comet attract General attention. Their appearance in ancient times was feared and perceived as a heavenly sign of the coming of the terrible events.

Medieval tapestry depicting the comet Halley
Human history in ancient times was very full of tragic events, such as wars, epidemics, Palace coups, assassinations of rulers. Some of these events have been accompanied by the appearance of bright comets, and predictors began to link the phenomena of heaven and earth.
In this famous old French tapestry in the time of William the Conqueror shows Halley's comet during its appearance in 1066. In that year a battle took place, in which the Duke had defeated the Anglo-Saxon army of king Harold II and took the English throne. This victory then attributed to the influence of the heavenly signs of the comet. The inscription on the tapestry says - I marvel at the stars.

In fact, the comet may not have as significant impact on our planet because of their tiny sizes: the mass of the comet is about a billion times less than the mass of the Earth, and the density of the substance of the tail is practically zero. So, in may 1910, the Earth passed through the tail of Halley's comet, but no changes have not experienced.

Death comet of chumacero-levy-9 in the gravitational field of Jupiter
Death comet of chumacero-levy-9 in the gravitational field of Jupiter
The comet was closer to Jupiter in 1992 and was torn by the force of its gravity. In July 1994 it fragments collided with Jupiter, causing fantastic effects in the atmosphere of the planet.
The comet was discovered on 24 March 1993, when she was a chain of fragments.

On the origin of comets are remnants of the primary substance of the Solar system. Therefore, their study helps to restore the picture of the formation of planets, including the Earth.

The most famous comet is Halley's comet.

Halley and open them comet
Halley's Comet

The period of revolution around the Sun the comet 76 years, the semimajor axis of the orbit and 17,8. e, the eccentricity of 0.97, the orbital inclination to the Ecliptic plane 162,2°, the distance at perihelion 0,59. that is, the Size of Halley's comet is 14 km long and 7.5 km in diameter.

Thanks to her English astronomer Edmund Halley discovered the periodicity of the appearance of comets. Comparing the parameters of the orbits of several brightest comets of the past, he concluded that it is not different comets, and the same, periodically returning to the Sun in a highly elongated path. He predicted the return of this comet, and his prognosis was brilliantly confirmed. This comet was named after him.

With 239 BC comet Halley was observed 30 times. The last time she appeared in 1986 and will next be seen in 2061, last visit cosmic ladies in our region studied it up close 5 interplanetary probes - two Japanese ("Sakigake and Suisei"), two Soviet VEGA-1 and VEGA-2") and one European ("Giotto").


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