Cassinian division
The Cassini division is the largest gap within the ring system of the planet Saturn . In calm air you can see them in good amateur telescopes with an aperture of 15 to 20 cm and from 150x magnification. However, it is noticeable from an opening of about 6 cm and a magnification of 120 times.
It is mainly caused by the moon Mimas , is around 4800 km wide and separates the two most striking rings of Saturn , the A-ring and the B-ring. There are always empty spaces between the individual Saturn rings, of which the Cassinian division is the largest. Due to orbital disturbances of Saturn's moons, the particles drift in or out from this area. The Cassinian division, however, is not completely empty space, but contains darker material, which is why it appears “empty” or without material on images taken by space probes.
The Cassini division is named after the Italian-French astronomer Giovanni Domenico Cassini , who discovered it in 1675 . As early as 1917, the partial transparency of the A-ring and the almost complete emptiness of the Cassini gap could be determined in one of the rare star occultations by the planet.
When the Kirkwood gaps in the system of minor planets were explored around 1870 , similar resonance effects of some of Saturn's moons on the rings could be demonstrated. It turned out that any particles in the Cassini gap would have about half the orbital time of Saturn's moon Mimas - and thus have unstable orbits. There are also integer resonances with some moons circling further out.
More precise measurements were made in 1980/81 by the two US space probes Voyager 1 and Voyager 2 . The latter discovered four other very thin particle rings in the gap. The edge of the Cassini division is formed by two dark rings 500–800 km wide, the contrast of which makes the division appear very sharp in terrestrial telescopes.
The Cassini space probe discovered a still unknown ring in 2006 during recordings while the Sun was being covered by Saturn (from the probe's point of view, September 15, 2006).
See also: Encke division
swell
- ↑ Patrick Moore et al .: Atlas of the Solar System , Chapter Saturn Rings . Herder-Verlag, Freiburg-Basel-Vienna 1985
- ↑ Stars and Space , 12/2006, p. 17