Why are Saturn's rings the only planet's we can see through a telescope?
Why are Saturn's rings so noticeable? Why are they much more visible than rings round other Solar System planets?
Why can’t we observe planetary rings other than Saturn’s? The answer is simple: Saturn’s ring system is the only one substantial enough to be visible through the eyepiece of an average amateur telescope.
This is because Saturn’s rings are composed of countless highly reflective particles, while the components of the other ring systems are narrower and made up of less reflective matter.
Moreover, Uranus and Neptune are much further away than Saturn, so their narrow rings are just a few arcseconds across in the night sky.
Even Saturn’s rings disappear for a short while when they are presented exactly edge-on to us at every half-orbit of Saturn (every 15 years).
Jupiter’s rings were discovered by the Voyager 1 spaceprobe in 1979.
Uranus’s rings were discovered in 1977 when a star due to be occulted by the planet winked on and off as the narrow rings produced a series of occultations on either side.
Occultation studies during the 1980s also provided evidence for Neptune’s ring system.
Since Uranus and Neptune occult stars bright enough to be visible through amateur telescopes, there are opportunities to observe occultations by their ring systems.
This guide originally appeared in the May 2006 issue of BBC Sky at Night Magazine.
Peter Grego was a popular amateur astronomer and the author of several books on practical astronomy. He passed away in 2016. Minor planet 95935 Grego was named in his honour.