New dwarf moon in the ring system waves

Cassini probe discovers hitherto unknown Saturn moon

New Saturn Moon in the Keeler Lips NASA / JPL
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In a spectacular prelude to their first season of ring observations, the Cassini probe has discovered a previously unknown Saturn moon. He hides in a gap in the outer A-ring of the planet. Waves in the surrounding ring material gave the astronomers first indications of its presence, new images of the probe now confirm the evidence.

The probe sighted the new moon, initially provisionally baptized by astronomers S / 2005 S1, first on May 1, as it slightly changed its orbit around Saturn. A day later, the on-board cameras delivered a clear picture of the newly discovered celestial body, which already allowed conclusions on size and brightness.

Second dwarf in the ring system

The pictures show the moon, which has a diameter of about seven kilometers and belongs to the dwarves in the Saturn system, in the center of the Keeler gap. This is located about 250 kilometers from the outer edge of the A-ring and reveals at its edges waves, which are due to the influence of the attraction of the small moon.

The new moon reflects about half of the light that strikes it and behaves in a similar way to the particles of the surrounding rings. "It's still too early to determine the exact shape of its orbit, but what we've seen of its motion suggests it's relatively close to the center of the gap, " explains Joseph Spitale, planetary scientist at the Space Research Institute in Boulder, Colorado. Further observations will now clarify whether the orbit is circular or elliptical.

S / 2005 S1 is the second moon discovered within Saturn's inner ring system. In addition to the 25 kilometer diameter rather small Pan, which circles in the Encke gap, move all other moons of Saturn outside of the main ring system. display

Wave on the outer edge

Scientists from the image analysis team had already predicted the presence of the new moon last July. Your clue: Strange peaks and stripes on the outer edge of the Keeler gap. Similar phenomena also show Saturn's F-ring and the Encke gap, which are influenced by moons circling in them. The conclusion that there might also be a small celestial body in the Keeler gap was therefore obvious.

"The obvious effects of this moon on the surrounding material will allow us to determine its mass and test our understanding of how rings and moons interact, " explains Professor Carl Murray of the University of London. According to astronomers, the new moon, like other moons outside the rings, could be relatively porous. From his poetry, the researchers can gain valuable clues about how and when the moon originated and what collisions he may already have behind him.

"Moon-embedded moons are among the most interesting dynamic systems we want to study with Cassini, " said Carolyn Porco, head of the image analysis team at the Space Research Institute. By studying how such a body interacts with the surrounding ring material, we can learn a little about how the planets formed from the dust and gas clouds in our solar system. We believe that many of the holes in the Saturn rings have embedded moons. We will now look for them. Further observations will follow over the next few months.

(Particle Physics and Astronomy Research Council (PPARC), May 12, 2005 - NPO)