Rings of the Solar System

April 2015  :  Francine Jackson

When I was a kid, apparently in the Dark Ages, we were happy to know that there was a beautiful ringed planet that we could see in just about every astronomy book ever printed.  Then, in 1977, a major jolt came, when Uranus was discover to have some type of ring system around it.  This caused a change in the Voyager space craft program, as both Voyager 1 and 2, on their way to the outer part of the solar system, were now charged with determining whether Jupiter also carried rings on its orbital path.  And, now that three of the Jovian planets had material circling them, logic dictated we finish the group, and, sure enough, Neptune also is surrounded by a set of rings.  

Doubly surprising is that every ring set is totally different from the others.  Saturn, of course, still has the only ones visible for all to see, from binocular observations which change the shape of Saturn to a tiny football, to the actual beauty visible even from rather small telescopes.  However, to this day, the actual reason why they’re present is still under debate.

The other three ring systems are virtually impossible to see.  Only the Hubble telescope is capable of picking up rings around Uranus, but only the brightest of the approximate dozen known.  And, of the three newer ring systems, only the rings of Jupiter seem to have an explanation for their presence:  Debris from impacts of the four small satellites lodged between Jupiter and the large volcanic moon Io circling Jupiter for a time.  Although the material eventually circles into Jupiter, more dust is always leaving the surfaces of these tiny moons.  

And now, it appears our Jovian planets aren’t the only ring worlds.  Last year, a tiny member of the Centaur class – objects considered hybrid asteroids/comets traveling in the solar system mainly between Jupiter and Neptune – also had a ring detected around it.  Chariklo, barely 200 miles in diameter, has a set of two rings, apparently partly composed of water ice.  

Recently, the original Centaur, Chiron, was found to possibly possess a ring, also.  Classified as centaurs, mythical half man/half beast because of their apparent double life, this set of objects could consist of thousands within this part of our neighborhood.  And, to now potentially be a type of object that could have ring systems like the large planets, this is a very exciting possibility, for, if these two minor planets are ringed, how many others could be out there?  The total of ringed objects is now six.  Hopefully, that number will become higher in the coming years, and it seems as if this is the class of objects where they might be.