Space and Earth
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.
Under the action of solar light pressure plasma, gas and dust emanating from the nucleus, constitute the tail length in millionai tens of millions of kilometers, directed away from the Sun (Fig.11). Quite a large speck of dust and pebbles gradually distributed along the comet’s orbit. If it crosses Earth’s orbit, at certain times of the year when the Earth is close to the corresponding point of intersection, one can see a lot of meteors (“shooting stars”). Meteor is not that other, as the light phenomenon (at heights of 80 – 120 km) arising from the intrusion into the earth’s atmosphere meteoroids – pieces of the former comet . The particles are so small that they are completely destroyed, not having time to reach the Earth’s surface. They make themselves felt suddenly appearing and quickly disappearing light strip. If such strips to represent on the star map, it appears that the lines cross approximately the same point. It is called the radiant of a meteor shower .
On average, after midnight, the meteors are observed twice as often than in the first half of the night. One explanation is that in the second case, the phenomenon of meteoroids cause meteor catching up with the Earth (during its motion around the Sun). The relative velocity of the particles when entering the atmosphere is less than in the case when they move towards the Ground (often after midnight). Moreover, as observations show, most of the meteors appear from July to November. Method of radar meteors (or rather, the ionized air trail of a meteor) can be observed in the daytime. To the naked eye, these meteors could be seen only during total solar eclipses.
Meteors, not inferior in brightness to the moon young are called fireballs . Them, in principle, can be observed at any time of the day, but they occur very rarely. Flight of meteoroids that causes the phenomenon of the car, in some cases, ends with the fall of the meteorite. To facilitate his quest, should measure maximum angular height of the meteor above the horizon and remember the direction of the point of intersection of the trajectory of the car with the horizon.
The phenomenon of the car is sometimes accompanied by sound effects (gradually fading thunder, and sometimes the rustle).
The most bright bolides is usually associated with large meteoroids arriving from the asteroid belt. Meteors not belonging to known meteor showers are called sporadic. The following are examples of meteor showers.
Cassiopeia . The radiant is in the constellation Cassiopeia. The greatest activity falls on July 28.
The Perseid . Perseus – 11-12 August.
Brigidi . Auriga – 30 August.
Orionid . Orion – October 22.
The Geminids . Gemini – December 13.
The fireball from the Leonid meteor shower
There is a belief that if you make a wish while a meteor is observed, it is necessarily true. Meteor like checks the power of desire. If the examination is sustained, thereby affirms the determination to fight for the fulfillment of a wish. But it is very difficult to have time to recall and verbalize a desire for the split second that it takes the phenomenon of the meteor.