Cassini unveils images of Saturn’s `glowing` rings

Washington – The rings of Saturn and the dark side of the planet can be seen glowing in the newly released infrared images by NASA’s Cassini spacecraft.

Matt Hedman, a participating scientist based at the University of Idaho, Moscow, Idaho, said that the parts of Saturn’s rings that are bright when you look at them from backyard telescopes on Earth are dark, and other parts that are typically dark glow brightly in this view.

It can be difficult for scientists to get a good look at the faint outer F, E and G rings, or the tenuous inner ring known as the D ring when light is shining directly on them.

That’s because they are almost transparent and composed of small particles that do not reflect light well. What’s different about this viewing geometry?

1. When these small particles are lit from behind, they show up like fog in the headlights of an oncoming vehicle.

2. The C ring also appears relatively bright here; not because it is made of dust, but because the material in it — mostly dirty water ice — is translucent. In fact, in the 18th and 19th centuries, it was known as the “crepe ring” because of its supposed similarity to crepe paper.

3. The wide, middle ring known as the B ring — one of the easiest to see from Earth through telescopes because it is densely packed with chunks of bright water ice — looks dark in these images because it is so thick that it blocks almost all of the sunlight shining behind it.

Infrared images also show thermal, or heat, radiation. While a visible-light image from  this vantage point would simply show the face of the planet as dimly lit by sunlight  reflected off the rings, Saturn glows brightly in this view because of heat from Saturn’s  interior.

In a second version of the image, scientists “stretched” or exaggerated the contrast of the data, which brings out subtleties not initially visible.