Saturn is the sixth planet from the Sun and the second largest planet in our solar system. It is famous for its dazzling system of icy rings.
However, these rings will temporarily disappear due to Saturn’s equinox.
When the Sun shines directly overhead at the equator on a planet, it is said to be the equinox. On Earth, it takes place in March and September, and it happens twice a year in every orbit. At the equinox, the Sun rises in the east and sets in the west, making day and night about equal.
Saturn’s equinoxes occur approximately every 15 Earth years. The international Cassini mission captured a Saturnian equinox for the first time on 12 August 2009. The next one will take place on 6 May 2025.
The rings are seen edge-on and appear as a narrow line when viewed from Earth during Saturn‘s equinox, occasionally creating the impression that they disappeared. But in this picture, Cassini was looking at the planet from 847,000 kilometers away, with a vantage point 20 degrees above the ring plane. This mosaic was produced by aligning and combining 75 shots that its wide-angle camera captured over eight hours.
The Sun’s direct light on the rings causes the shadows cast on the planet to appear as a thin band. Additionally, the rings seem darker than usual. As a result, out-of-plane structures may appear brighter than usual, casting shadows over the rings. It’s only a few months before and after the equinox that these Saturnian shadow puppets appear.
The shadows Cassini observed revealed previously undiscovered moonlets and brand-new “mountains” in the rings. On the B ring on the right side of the picture, there are additional radial patterns that are referred to as spokes.