Satellite shows Saturn moon might have rings (AP/CNN)

[eppur_se_muova]

PASADENA, California (AP) -- New observations by a spacecraft suggest Saturn's second-largest moon may be surrounded by rings.

If confirmed, it would the first time a ring system has been found around a moon.

The international Cassini spacecraft detected what appeared to be a large debris disk around the 950-mile-wide moon Rhea during a flyby in 2005. Scientists proposed that the halo likely contained particles ranging from the size of grains to boulders.

The finding was described in a study published in the March 7 issue of the journal Science.

Unlike the rings around Saturn, Jupiter, Uranus and Neptune, the apparent arcs around Rhea remain invisible and have not been directly seen. Scientists inferred their existence based on measurements by Cassini, which detected a drop in electrons on both sides of the moon, suggesting the presence of rings was absorbing the electrons.
***
more: http://www.cnn.com/2008/TECH/space/03/06/saturn.moon.ap/index.html

[MikeNearMcChord]

1. Wow!! Saturn is incredible, what more surprises does this

planet have?

[Ian David]

2. A drop in Electrons could also be caused by a mass of Positrons orbiting the moon.

Certainly not the LIKELY cause, but it would sure be interesting!

[caraher]

3. I'd think there'd be a pretty obvious 511 keV gamma ray signal

Positrons and electrons don't exactly vanish without a trace when they hook up!

But this does make me wonder how well-equipped various space probes have been to analyze the gamma ray spectrum in these environments. There might be a larger window for surprises than we might think (it's awfully hard to find things you didn't have the foresight to look for!)