Meteor shower

In addition to individually occurring ( sporadic ) meteors there are meteor showers (even meteor showers or shooting stars swarm, often mistakenly also meteor shower ). They are a cluster of shooting stars at certain seasons, the tracks of these small bodies in space are parallel.

Formation of meteor swarms

Shooting stars or meteor showers can occur when the earth on the move around the sun gets close to a comet train or it crosses approximate. In perihelion comets lose constantly a part of their mass in the form of gas and dust ( comet tail ) of rock fragments and other small particles, called meteoroids. They are spread over the millennia over the entire orbit of the comet, which is why a meteor stream annually recurs usually at the point where the Earth flies through the region of this cloud of matter. The strength of a meteor shower is specified as Zenithal Hourly Rate ( ZHR ); it is the hourly number of meteors that are visible to the climax under ideal conditions.

Temporal variation of meteors and their Radiant

As a rule, most meteors in the early morning sky in the east - just before dawn - to see, because the observer then them " counter rotating " as a result of Earth's rotation.

All of a meteor shower meteors seem to come here from the same point in the sky, the radians. The naming of the meteor shower is usually done after the constellation in which the radiant lies (eg Perseids: constellation Perseus ). However, its celestial coordinates change when a meteor swarm lasts longer than a few days, because the elliptical orbits of the particles around the sun has a curvature which accounts for about 1 ° per day.

The particle density on the trajectory of the comet is just before and after the flyby of the comet on the sun significantly greater. This event is called a meteor storm, which in some years more than a thousand meteors can be seen per hour.

There may be a particularly large number of meteors even several years after the perihelion of the comet, such as at the 2002 Leonids and the perihelion passage in 1998 of the associated comet Tempel-Tuttle.

As dissolve these particle clouds over the years and their paths can be changed by the sun through perturbations and other gravitational or non- gravitational influences disappear meteor streams in the long term (such as the Leonids after 2002 ), while new flows from the current (still "active" ) comets arise.

Annually recurring meteor showers

The following table is an excerpt from the list of meteor streams and contains only the largest of these flows, which may have more than about ten meteors per hour. The two most important ( Perseids and Geminids ) are highlighted in bold.