Ripples found in the ring systems of Saturn were caused by comets that collided with the rings in 1994.
Ripples in Jupiter’s rings were also found and are believed to have been caused by the comet Shoemaker-Levy 9.
Researchers re-analysed images of Jupiter’s rings taken by the Galileo spacecraft in 1996 and 2000 and by the New Horizons probe in 2007. They also looked at images of Saturn’s rings taken by the Cassini spacecraft during 2009.
They found undulations that they likened to a corrugated tin roof, which when lit from a low angle, appear as alternating dark and light bands.