During Galileo Galilei’s initial observations of Saturn’s rings through his telescope in the early 17th century, he was mystified to find the planet’s “appendages” appear, disappear, and reappear over the course of 6 years. Why was this the case?
It soon became understood that during the period of disappearance, Earth was crossing Saturn’s ring plane, causing the rings of the planet to all but disappear. Much like Galileo’s view a few hundred years ago, the Cassini image above is indicative of how incredibly thin the rings are. The main rings are generally only 30 feet thick, though parts of the main and outer rings can be several kilometres thick. Over astronomical distances, its no surprise the rings can simply disappear!
“Saturn’s thin ring plane appears in blue, bands and clouds in Saturn’s upper atmosphere appear in gold. Details of Saturn’s rings can be seen in the high dark shadows across the top of this image, taken back in 2005. Moons appear as bumps in the rings.”