Meteor shower - many meteors, which seem to be emanating from a single point in the sky and observed for a limited period (usually a few hours or days). Meteor showers occur when Earth in its orbital motion crosses meteor swarm (extended accumulation of meteoric matter in orbit around the Sun).

There are many annual flows, although only some of them produce meteor showers. Very rare Earth is facing a particularly dense swarm of particles, and may then be exceptionally strong flow with dozens or hundreds of meteors every minute. Usually good regular flow gives about 50 meteors per hour.

Members of the flow are characterized by the fact that their trajectories are tracked "reverse"seem to intersect at a single point in the sky, called the radiant. This illusion is a perspective effect. Meteors are generated by the particles within the upper layers of the atmosphere on parallel paths.

The earth at this time are met not a single meteor particle, and a swarm or a cloud of such particles meteor shower. All particles flux fly in space parallel to each other and seem to be flying only because of the prospect. Recall that a railroad track or tree-lined alleys, too, seem to be diverging from distant points, whereas in reality they are parallel to each other.

Annually known in the days of the Earth crosses the orbits of rich meteor showers. At this time there is especially frequent appearance of meteors in a certain area of the sky. Meteor shower called by the name of the constellation in which is the radiant flux.

Italian scientist Schiaparelli in the last century, and later Bredikhin proved that flows meteors moving in orbits, which had moved extinct comet. It turned out that flows meteors are products of the gradual disintegration of cometary nuclei. Sometimes the collapse does not occur gradually, and very quickly. There are cases when the nucleus of comets in the eyes of the observers in the continuation of a few days were shattered into several pieces.

After partial or complete decay of the nucleus of comet before her, and even more after her along the orbit stretches out the flurry of dust and small rocks of Meteora. They all gradually dissipate, and when the string of them becomes very wide, the opportunity to meet them with the Earth increases.

Types of meteor showers:

Aquarids

This is Aquarids observed between April 24 and may 20 (usually 4-5 may). This is a lovely South meteor shower associated with Halley's comet 1P/Halley). His radiant is located at the point with RA 22h 20m, Dec. -1 degrees. The average density of dropping out of the maximum of 35.

Delta Aquarids observed between July 15 and August 20, with peaks 29 July and 7 August. Have double radiant, the components of which are in the points with RA 22h 36m, Dec. -17 degrees and RA 23h 04m, Dec. +2 degrees. The average density of dropping out of the maximum of 20.

The Draconid

The thread associated with the comet Giacobini-Zinner, which can sometimes be observed about 9-10 October. The radiant lies near head" Dragon in the point with RA 17h 23m and Dec. + 57 degrees. The number recorded for the year of meteors from year to year changes greatly. So, in 1933, was observed spectacular sight when the flow quickly reached 350 per minute, which again was noted only in 1946 Moderate showers occurred in 1952 and 1985 This thread also known as "Jacobinize".

Lyrid

Annual meteor shower, sometimes called the April Lyrid. His radiant lies on the border of the constellations Lira and Hercules. Peak meteor shower falls on April 22, the usual time of its appearance from 19 to 25 April. Meteor shower associated with comet of Thatcher (C/1861 G1). Although usually meteor shower sometimes weak, sometimes there are beautiful showers. The average density of dropping out of the maximum of 10. Historically meteor shower the Lyrids traced over 2500 years.

The quadrantids

Annual meteor shower, the source of which lies in the constellation of Bootes,near the border with the constellation of Hercules and the Dragon. The name refers to the time when this area of the sky belonged to the constellation Mural Quadrant (Quadrans Muralis), now does not exist.

The peak of a meteor shower falls on January 3, and the normal limits - from 1 to 6 January. A narrow stream of meteors is not associated with any known comets, and the resulting stellar rain is very irregular, so its peak does not last long.

Geminid

Annual meteor shower, the source of which lies in the constellation Gemini (near the stars castor). The maximum flow is from December 13, and the most frequent time of his appearance - 7-16 December. This meteor shower has an unusual orbit with a perihelion distance of only 0.14 AU

Orionids

Annual meteor shower, multiple radiant which lies on the border of the constellations of Orion and Gemini, near the star gamma Twins. Peak flow falls on 22 October, and the normal limits of its appearance - from 16 to 27 October. The thread has to do with meteoroids that came to Earth from the comet Halley.

Leonids

Annual meteor shower, radiant lies in "the sickle" constellation of Leo. Peak flow falls on November 17, and the usual duration - about four days. Although these days every year there is only a small number of meteors, sometimes there and exciting spectacle. So, in 1966, it was possible to see up to 40 meteors per second!

Meteor shower associated with comet 55P/Tempel-Tuts, first registered in 1865, which has a period of 33 years. Meteor substance is concentrated around the comet and not distributed evenly along the orbit. So beautiful spectacle possible only time in 33 years, although in this case they are not mandatory, especially if the comet goes too far from the Earth's orbit.

The Perseids

Strong annual meteor shower, radiant which lies close to the star This Perseus. Peak flow falls on 12-13 August, and its normal limits - from July 23 to August 20.

Meteor shower associated with comet 109P/swift-tuttle. This is one of the most beautiful and stable annual flow with maximum intensities of 50 to 100 meteors per hour.

The Taurids

Annual quite weak (3-5 meteors per hour) meteor shower, double radiant lies in the constellation of Taurus. Peak flow falls on 3 November, the boundaries between 13 September and 29 November.

Meteor shower associated with comet Encke.