Saturn's rings light up with bright blue highlights, in this blend of both visual and X-ray observations.

Astronomers believe that fluorescence caused when solar X-rays smack into the oxygen molecules locked with in Saturn’s icy ring water.

As seen in this image, most of the X-rays among Saturn’s rings come from the B ring, the bright white, inner ring in the optical image of the planet.

There is some evidence for a concentration of X-rays on the morning side (left side, also called the East ansa) of the rings, possibly because X-rays are associated with optical features called spokes that are largely confined to the dense B ring and most often seen on the morning side.

Spokes are due to transient clouds of fine ice-dust particles that are lifted off the ring surface. It has been suggested that the spokes are triggered by meteoroid impacts, which are more likely in the midnight to early morning hours because during that period the relative speed of the rings through a cloud of meteoroids would be greater.

The higher X-ray brightness on the morning side of the rings could be due to the additional solar fluorescence from the transient ice clouds that produce the spokes. This explanation may also account for other Chandra observations of Saturn, which show that the X-ray brightness of the rings varies significantly from one week to the next.

• X-ray Image of Saturn Puzzles Scientists

-- SPACE.com Staff

Credit: X-ray: NASA/MSFC/CXC/A.Bhardwaj et al.; Optical: NASA/ESA/STScI/AURA