Thursday, July 19, 2007

New Moon


On May 30 our Cassini spacecraft observed S/2004 S7, the 60th known satellite of Saturn. This moon is approximately 2 km across and orbits 1.76 million km from Saturn. This orbit is between those of moons Mehone and Pallene, which were also discovered by Cassini. The Rings contain countless undiscovered objects, some of which are big enough to be called moons.

Photo below was taken June 5. The moon Pan leaves big wakes in the Encke Gap. The Gap's boundaries mark inner and outer Lagrangian points in the Pan-Saturn system. Particles within this gap are drawn into Pan's gravitational field. Presence of this moon maintains the Encke gap. Since the Rings contain thousands of such gaps, there are many more large undiscovered objects out there.

To the right moon Prometheus leaves big gaps in the F Ring. Prometheus and Pandora are called shepherd moons because they appear to hold F Ring in place. At one time the Rings were thought to exist inside a mathematical "Roche Limit." Outside this limit moons could exist, and inside they would break up tidally to form Ring fragments. Prometheus has a density of barely 0.27 g/cc, barely 1/4 that of liquid water. It is odd that objects with a density less than liquid exist inside the Roche Limit, within which liquid objects are not supposed to exist at all.

As seen here, Prometheus leaves big gaps in the F Ring, causing particles to spiral toward the moon. No one is sure about the nature of this interaction, but it is like that of a magnetic field. Presence of a magnetic field from a tiny moon would be indication of a singularity. If Prometheus' 10^17 kg mass contained a 10^11 kg singularity, the moon would not collapse. Presence of a singularity would hold Prometheus together despite being within Roche's Limit. The singularity would rotate within Prometheus, powering a magnetic field.

Today we have discovered 60 moons of Saturn. This solar system contains hindreds of unexplored worlds, many of which could be home to life. This photo could contain dozens of Black Holes. There is far more in the Universe than meets the eye.

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2 Comments:

Blogger nige said...

Amazing discovery. I wonder how stable the orbit of this tiny moon is, and whether there's any risk of such a moon colliding with another moon (or, worse, being catapulted towards us by the deflection caused by a near-miss)?

4:58 AM  
Blogger L. Riofrio said...

There have probably been many moon-moon collisions in history. but Saturnian moons lack the velocity to threaten Earth.

4:22 PM  

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