Ray system

A ray system is in astronomy a grouping conspicuous, called a beam stripes that are arranged radially in the typical case is a located in the center crater, called a ray crater.

Description

Beam systems are known mainly from the moon. The beams look like spray tracks and are usually lighter than their surroundings. Most striking, they are at high sun and also vertical viewing direction - from the earth at full moon - in contrast, when blurred the outlines of craters and other details in the light. For side lighting the radiating strip cast no shadows, therefore they have no relief. The rays are up to several kilometers wide and extend straight or curved to many hundreds of kilometers over hill and dale. They go through Highlanders as well as lowlands often without deviations or interruptions and thin in its brightness with increasing distance from the central crater in general more or less gradually from.

The appearance of the beams is explained by a composition of powdered material that was ejected by a large impact in the development of the central crater; or with glass -like particles, which are vaporized by the high energy of impact rock had solidified again and which are responsible for the high reflectivity.

The relatively few and mostly central crater rays have a similarly high albedo as a rule and are of very regular shape. Thus, the overall structure gives the impression of a fresh appearance and thus a relatively young age. It is believed that the bright substance the sunlight reflects the stronger, the less it was exposed to the particles of the solar wind, cosmic radiation, and the hail of micrometeorites since its creation. The small number of large systems of rays is attributed to a decline in frequency of large impacts. Most lunar craters have no radial stripes.

Many of the at first glance seemingly continuous- rays have a much changing intensity. Sometimes they also put off temporarily, and consist of a series of individual strips that are roughly aligned with the central crater. Also, a total of not always true, the beam center line with the center of the impact crater. The rays rely on only some distance from the crater wall, which is therefore separated by a darker overall appearing ring zone of the approach circle of fabric. Some rays contain large blocks of rock and run over small secondary craters, of which emanate rays. Some small craters have to your Wall only a bright courtyard.

The biggest ray system on the moon has a diameter of 85 km wide crater Tycho. Its bright radial stripes run up to a distance of about 1800 kilometers. Other well-known ray crater on the Moon are Copernicus, Kepler, Aristarchus and Proclus.

Also on other bodies in the solar system has found Crater rays, such as on the outside moon-like planet Mercury, as well as among the large satellites of Jupiter on Europa, Ganymede and Callisto. In celestial bodies with a dense atmosphere like Venus or with a thin as the Mars such radial structures are obliterated by erosion is much faster again.