Stars you would escape, Asteroids and Comets

 

The Asteroids are great pieces of rock and metal that go from the few meters to hundreds of kilometers of extension. Most of the Asteroids are in a ring between Mars and Jupiter that is called the Belt of Asteorides.

Ceres: one of the greatest asteroids ceres asteroid

 

yellow spacey

 

meteors

In some ocación we have been able to observe what we called a fleeting star. Its scientific name is “meteor?, that is not more than a rock piece that when entering the Earth atmosphere warms up so much (by the friction with the air) that begins to shine. Sometimes of the year many meteroros can be seen falling the Earth (they are possible to be counted sometimes up to 100 in an hour). These are the calls meteor rains that happen when the Earth moves by a zone through which it passed a comet leaving pieces of itself.

When a comet happens through the interior of the Solar System, the interaction with the solar wind causes that its surface activates. The gases and materials of the surface of the comet leave dismissed the space, and happen to orbit to the Sun in orbits very similar to those of their comet of origin. Thus a particle current or ring forms, denominated meteor cluster technically. The Earth orbit crosses some comet clusters of short period, producing annual meteor rains, as the Leónidas or the Perseidas. When the activity of a meteor rain exceeds 1000 meteors per hour, is denominated it meteor storm.

One thinks that some asteroids can be exhausted comets, that is to say, comets that are lost all volatile elements. For that reason, some of these phenomena has to asteroids as body ancestor. It is the case of the Gemínidas, that they are in the orbit of the asteroid (3200) Phaeton.

When entering a meteor the terrestrial atmosphere, is observed a luminous outline called fleeting star or meteor. This luminous radiation is produced by the ionization of the atmosphere that generates the particle. Most of meteors have the grain size of sand and 80 or 100 kilometers of height are disintegrated to about. Some with greater mass get to have a considerable brightness, and it denominates them bolides (in English, fireballs). Only when the meteoroids own a considerable mass can completely atraversar the atmosphere until arriving at the surface. These meteoroids happen to receive the meteorite denomination.

You can see

Lluviade meteors this page for more information!

 

The radian is the imaginary point in the sky from which they seem to come meteors. You can find the radian in the photo of above?

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Sometimes the rocks that enter the Earth atmosphere are too great and not quemam porla friction completely, gets to fall to the ground and meteorites are called. The meteorites get to create great craters as the one of Arizona, EE.UU., which you can see the left.

The term meteor comes from Greek meteoron, that means phenomenon in the sky. One is used to describe the flare produced by the fall of the matter that exists in the Solar System on the terrestrial atmosphere what gives rise to a temporary incandescence result of the atmospheric friction. This happens generally to heights between 80 and 110 kilometers (50 to 68 miles) on the Earth surface. This term also is used in the word meteoroid with which we talked about to the own particle without no relation with the phenomenon that produces when it enters the Earth atmosphere. A meteoroid is the matter that turns around the Sun or any object of the inter-planetary space that is too small to be considered as an asteroid or a comet. The particles that are smaller still receive the name of micrometeoroides or stellar dust grains, which includes any interstellar matter that could enter the Solar System. A meteorite is a meteoroid that reaches the Earth surface without it has been vaporized completely.

 

The comets are masses of ice, dust and rocks that wander by elespacio. As the rest of the celestial bodies in the Solar System orbits (they turn) around the Sun. When approaching more and more the Sun, the ice melts and a tail grows to him. As the comets turn around the Sun can be seen time and time again, although often it is necessary to hope whole years to return to see them. The comet of Halley can be seen from the Earth every 76 years. It was possible to be seen for the last time in 1986 reason why we will have to hope almost a century to return it to see. As the comets come near to the Sun they develop enormous tails of material luminous that extend by million kilometers from the head, moving away of the Sun. When they are far from the Sun, the nucleus is very cold and its material is frozen. Sometimes in this state the comets receive the name of “dirty iceberg? or “dirty snow ball?. When a comet comes near to the Sun, to few UA (astronomical units) of the Sun, the surface of the nucleus begins to warm up itself and the volatile ones evaporate. The evaporated molecules follow and drag with them small solid particles forming the hair of the comet, of gas and dust.

When the nucleus is frozen, it can be only seen due to the reflected sunlight. Nevertheless, when the hair is created, the dust reflects more sunlight and the gas of the hair absorbs the ultraviolet radiation and begins to fluorescer. To some 5 UA of the sun, the fluorescence are made generally more intense than the reflected light.

As the comet absorbs the ultraviolet light, the chemical processes give off hydrogen, that escapes to the gravity of the comet and forms one surrounded of hydrogen. This surrounded cannot be seen from the Earth since its light is absorbed by our atmosphere, but has been detected by the spaceships.

The pressure of the solar radiation and solar winds accelerates the materials moving away them of the head of the comet at different speeds in agreement with the size and mass of the materials. By this, the relatively massive dust tails are accelerated more slowly and lie down to being curved. The ionic tail is much less massive, and is accelerated so much that appears as an almost straight line that extends from the comet in the side opposed to the sun. The following image of the West Comet shows two different tails. The fine blue plasma tail is composed by gases and the white wide tail this composing by microscopic dust particles.

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Comet Haul 1997

 

dino

WISE PEOPLE WHO?

The scientists think that great asteroride or a comet was the one that caused the extinction of the dinosaurs. This teoriía was formulated by the Alvares scientists (father and son).

In 1980 a group of investigators led by the physicist Luis ?lvarez (Nobel prize) discovered, in the samples taken by everybody from the intermediate layers between the periods cretaceous and tertiary of he makes 65 million years, a iridium concentration hundreds of times higher than the normal thing. The end of the cretaceous one agrees with the extinction of the dinosaurs and ammonites.

They raised therefore the call “Alvarez Hypothesis? or “Hypothesis of Alvarez?, in agreement which the extinction of the dinosaurs and many other forms of life would have been caused by the impact of a great meteorite against the Earth surface makes 65 million years. The name of the hypothesis is due to scientists both who proposed the hypothesis in 1980: Luis Alvarez and Walter Alvarez (father and son). In order to demonstrate this hypothesis, the investigations concentrated in finding a layer in the Earth crust with iridium elevated levels. The levels of iridium are generally more stops in asteroids and other extraterrestrial objects. The evidence of iridium was discovered previously to the discovery of the crater of Chicxulub.

One of the majors objections to this hypothesis was that a crater was not known whose dimensions corresponded to the calculated size, that it must have between 150 and 200 km of diameter. Looking for realised geologic studies from years 1960 in future a crater in Chicxulub could be located, in the Yucatan Peninsula, with a diameter of about 170 km.

For some scientists, a problem of this theory is that the reading of the fossil registries suggests it massive extinction of makes 65 million years lasted near ten million years, which does not square well with which its cause was the impact.

 

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