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International Edition Winners 2012: Bulgaria

International Edition Winners 2012: Bulgaria

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Target 1, Pan
Deana Antonova Teneva

9a class FLS "Romain Rolland"
Director of studies: Nadia Kiskinova
Astronomer for NAOP "Y. Gagarin"

"The moon Pan is the innermost natural satellite of the planet Saturn. It's located on the inner edge of the A-ring and creates the Encke Gap, which is 320 km wide and is the corridor, in which the moon moves. By doing so, Pan sustains the form of the ring and doesn't allow for any material to escape. Because of this it and moons like it are called shepherds.It has a diameter of 20 km and a form slightly stretched at the equator, which can be described as a walnut.

Although information about the formation and internal structure of this small satellite could help us solve Saturn's ring's greatest mystery – their age and origin - we don't know that much about it. Before Voyager 1 arrived at Saturn in 1980 scientist thought that the ice particles, which compose the rings, were the leftover material from the planet's formation and the strong tidal forces didn't allow for the creation of moons. However, the discovery of Mimas–sized satellites and later Pan suggested that the material in the rings came from a moon, which underwent a catastrophic collision. This also could mean that different rings were formed from separate bodies at different times. Nevertheless, Voyager's results also show that Mimas–sized moons could have enough mass to create the rings for a short time before losing it and that's why the rings, as we know them today, should have been formed with the Solar System 4, 5 billion years ago. On the other hand, small satellites like Pan and Atlas couldn't have survived for long or reformed because of Saturn's strong tidal forces. The newest theory suggests that only the dcores of Pan and moons like it were part of a progenitor body and the material around them was attracted later. If this is proven correct through detail study of Pan's composition and structure, it would help explain the ring's formation.

In addition, Pan is interesting because its gravitational influence on the A-ring. Its main affect is clearly shown by the Encke Gap, but also harder to detect "wakes" can tell us a lot. Particles, which are closer to Saturn, move faster than Pan and because of that when they pass by it, they receive a gravitational push or kick. Bodies near the inner edge, which have already interacted with the moon and have continued, create wakes behind it and those near the outer edge are overtaken by the satellite and the wake is after it. These and similar phenomena help us understand better the dynamics of Saturn's rings and moons and deserve a thorough research.

All in all, the moon Pan offers great opportunities for exploration, which could lead to interesting results."