What do planetary rings do

Karkoschka University of Arizona. Webb will investigate their composition. Last Updated: May 31, What Makes Brown Dwarfs Unique? How Earth-like Are Exoplanets? Back to top. The moonlets launch the surrounding ring particles hundreds of feet meters above and below the ring, producing the features Cassini imaged. The ring particles are kicked up in the same way that a moving boat creates wake.

The ring particles nearer Saturn move faster than the moonlet while those farther from Saturn move slower than the moonlet, and the interaction is gravitational, causing wake to form both behind and in front of the moonlet as it orbits. On Aug. For half of a Saturn year, the ringed planet appears to bow toward the sun, which then illuminates the top of the rings. But Saturn takes about 30 Earth-years to orbit the sun, so its equinox happens only once every 15 years.

Countless icy clumps in the rings cast great shadows upon the rings. Some of the clumps and bumps were as tall as the Rocky Mountains. During equinox Cassini also monitored the temperature of the rings with an infrared spectrometer because temperature helps scientists understand the composition, size, shape and other characteristics of ring particles.

Because sunlight was hitting the rings on their edge rather than on their broad face, temperatures in the rings dropped lower than anyone had recorded there before.

Cassini saw the A-ring, for example, cool down to minus degrees Fahrenheit minus degrees Celsius. In addition, Cassini used the equinox to observe some known phenomena that are poorly understood. One of those features are the "spokes. Spokes are the ghostly radial markings discovered in the rings by NASA's Voyager spacecraft 25 years ago.

Sign up for our email newsletter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. Astrophysicist George F. Spagna, Jr. In the mids, there was a stellar occultation of Neptune and, just like Uranus, the starlight blinked before reaching the planet.

Scientists weren't convinced that Neptune's rings completely circled the planet, but instead were smaller arcs. It wasn't until Voyager 2 passed by in that the truth became known. Neptune had a complete ring system as well. From Earth, the rings look like a solid sheet of material, but they are actually made up of billions of particles of rock, ice and dust.

The particles range in size from miniscule and microscopic to the size of houses and cars. The brighter areas in the image to the right are reflecting more light from the Sun than the darker areas. The darker regions have fewer particles, so not as much light is reflected. The lighter regions are denser, so there are a lot of surfaces to reflect light. Saturn's rings are only a few tens of meters thick, but extend almost , km above Saturn's equator.

This is about a third of the distance from the Earth to the Moon. How can something extend so far, but be so thin? Since the rings are made of billions of individual particles, you can imagine how closely packed they are. Any object with an orbit even slightly inclined to the central plane will collide with other objects just about every time it passes through.