S/2009 S 1

Cassini Imaging Science Team

S/2009 S 1 is the innermost and smallest ever of the 62 known moons of the planet Saturn. He is the only previously known moon of Saturn's B ring of Saturn's rings. This is a so-called ' propeller moonlet '.

Discovery and designation

S/2009 S 1 was discovered on July 26, 2009 to an individual receiving the Cassini Imaging Science Team on the Cassini mission. The picture was a Nahwinkel recording of the B- ring during a crossing of the probe through the ring plane and was taken through a clear filter with an exposure time of 0.82 seconds and a resolution of about one kilometer. The moon fell on by a 36 km long shadow he cast on the dense outer B ring. As the light of the sun at the time of the equinox on 11 August 2009 - that about every 15 years will take place - as the rings of the planet shown at its edge to the sun and only a thin shadow line cast on Saturn, at a very shallow angle to the rings fell, S/2009 S 1 could be localized. He is the first and only discovered moon of the B ring, and the seventh moon discovered the Cassini space probe.

The discovery was announced on November 2, 2009 by Carolyn C. Porco known, the director of the Imaging Science Team of the Cassini mission. With it, the innermost and smallest at this time Saturn moon was discovered and the number of previously discovered satellites of Saturn rose to 62

The provisional designation S/2009 S 1 corresponds to the classification of the International Astronomical Union ( IAU). He is so far the only one of the so-called inner moonlets which received its own numbering and must therefore be regarded as a regular moon. In addition, he is so far the smallest numbered by the IAU moon in the solar system.

Web properties

S/2009 S 1 orbits Saturn on a prograde, probably perfect circular orbit at a distance of approximately 117,100 kilometers (about 1.943 Saturn radii, which is remarkable, since the innermost Neptune moon Naiad and the Uranus moon Cordelia in the ratio almost the same distance to their central planet is ) from its center, or about 56,700 km above the cloud tops. This means that he is the Saturn surface closer than the Saturn center itself, the orbital eccentricity and orbital inclination relative to the equator of Saturn has not yet been precisely determined because the moon so far could only be viewed on a single recording; However, both values ​​should be around the 0.0.

The orbit of the next outer moon Pan, who has held the status of the innermost of Saturn's moons to 2009, one located in the middle about 16,500 km from the orbit of S/2009 S.

S/2009 S 1 orbits Saturn within the outer approximately 26,600 km broad B- ring, the outer ring edge or the inner edge of the Cassini division is only removed about 480 km from the orbit of the moon. In contrast to the 2006 moonlets found in the A ring, the about 13,000 km further outwards are in the A ring, were to be found S/2009 S 1 no propeller-like structures. Said moonlets ( no numbering given ) were too small to be photographed directly, but were localized through the narrow gaps generated during their round. The absence of propeller structures in S/2009 S 1 is very plausible, since the B- ring is very tight and the gaps created by him would fill up more quickly than in a less dense region like the middle A ring. Besides, it is far more difficult for a small moon to create gaps at all in such a dense ring.

The orbital period could not be determined precisely, but would have to because of the distance to the central planet 11 hours, is 20 minutes and about 24 seconds. Since this is only a little more than Saturn's rotation period, would S/2009 S 1 over seen by a hypothetical observer of Saturn from very long time to be seen in the sky (assuming it could be due to the embedding in the B ring and the low size ever make ).

Physical Properties

S/2009 S 1 has a diameter of about 300 meters. The size of the moon was derived from the fact that he stood out about 150 meters above the ring plane during discovery.

Research

The only recording of the Cassini spacecraft can be seen on the S/2009 S 1, was made 16 days before the beginning of spring of Saturn's northern hemisphere from a distance of 296,000 km, when the probe is about 42 ° below the sunlit B- ring was located. Saturn itself was lit at this time from this position about two- thirds.

Gallery

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