Why do outer planets have rings

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. This constant collision will cause the object to slow down and eventually fall in with the rest of the pack.

There are a bunch of theories about how and why rings formed around the outer planets. Most of the focus has been placed on understanding the origin of Saturn's rings. We know that the rings are old, but the question is: How old?

Thousands of years? Millions of years? The solar system is about 4. That means that the rings formed when the solar system was still forming, about 4. While the rings themselves are thought to be as old as the solar system, the particles that make up the rings are very young. Older particles have been covered by interplanetary dust, leaving them less reflective.

The majority of the particles are bright, which means they haven't had time to collect dust. This suggests the ring particles get recycled somehow. Some scientists believe that the particles coalesce into moons and repeatedly break up again. The Cassini spacecraft recently discovered that Enceladus, one of Saturn's medium-sized moons, is providing new material to Saturn's E-ring.

The E-ring is the largest planetary ring in the solar system, and seems to be continually replenished by geologic activity on Enceladus. The rings around Saturn were discovered by an astronomer called Galileo Galilei nearly years ago. He used a very simple telescope that he constructed himself from lenses and pointed it at the planets in the night sky.

One of the first objects he looked at was Saturn. Since then, astronomers — who study the universe and everything in it, like planets — have used bigger and better telescopes to find rings around all of the outer gas giant planets: Jupiter, Saturn, Neptune and Uranus. These planets, unlike others in our system, consist largely of gas.

The first theory states that the rings formed at the same time as the planet. Some particles of gas and dust that the planets are made of were too far away from the core of the planet and could not be squashed together by gravity. They remained behind to form the ring system. The second theory , and my personal favourite, is that the rings were formed when two of the moons of the planet, which had formed at the same time as the planet, somehow got disturbed in their orbits and eventually crashed into each other an orbit is the circular path that the moon travels on around the planet.

The stuff that was left behind in this huge smash could not come together again to form a new moon. Instead, it spread out into the ring systems we see today.

Around Neptune, intermittent regions of thickly clustered particles, known as ring arcs, have been seen to split and evolve, but astronomers need more data to truly understand the processes taking place. Why Do Planets Have Rings? View All Articles. Though we think of rings as being passive, decorative elements to a planet, they're actually more like an extra-planetary surface.

Karkoschka University of Arizona. Webb will investigate their composition. Last Updated: May 31, What Makes Brown Dwarfs Unique?