Explanation:
What's happened to that moon of Saturn?
Nothing -- Saturn's moon Rhea is just partly hidden behind Saturn's rings.
In April, the robotic Cassini spacecraft now orbiting Saturn took this
narrow-angle view looking across the
Solar System's most
famous rings.
Rings visible in the foreground include the thin
F ring on the outside and the much wider
A and B rings just interior to it.
Although it seems to be hovering
over the rings, Saturn's moon
Janus is actually far behind them.
Janus is one of
Saturn's smaller
moons
and measures only about 180 kilometers across.
Farther out from the camera is the heavily cratered
Rhea, a much larger moon
measuring 1,500 kilometers across.
The top of Rhea is visible only through
gaps in the rings.
The Cassini mission around Saturn has
been extended to
2017
to better study the complex planetary system as its season changes from
equinox to
solstice.
