Encke division

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The rings of Saturn with their names (picture NASA). The Encke division is the slightly darker area between rings A and F. The wide Cassini gap is between A and B.

A circular gap on the outer edge of the A-ring , the second brightest of Saturn's rings , is called the Encke division .

It was discovered in 1837 by the Berlin astronomer Johann Encke and at that time estimated to be 300 km wide. According to measurements by Voyager space probes from 1980/81, it is 200 to 330 km. In contrast to the Cassini graduation, which is 20 times wider , it can no longer be seen in amateur telescopes , but only at a magnification of around 1000 times.

The Encke division is caused by orbital disturbances of nearby Saturn's moons , in particular by the shepherd's moon Pan , which revolves within the division , causing the particles to drift away from this area inwards or outwards. It is 2,000 km from the outer edge of the A and 133,500 km from the center of Saturn . Their distance from the cloud surface of the planet is 13,000 km.

When Voyager 2 flew away from Saturn, an eclipse of the star Delta Scorpii was taking place. Continuous brightness measurements showed that there are two thin, eccentric particle rings inside the Encke division. The irregularities in it have exactly the rotation time of 13.82 hours, which is typical for this area.

literature

  • Patrick Moore et al .: Atlas of the Solar System , p. 332-333. Herder-Verlag, Freiburg-Basel-Vienna 1985