Five Years Ago, Cassini Began Orbiting Saturn
NASA's Cassini mission has been orbiting Saturn for five Earth years as of June 30, 2009. That's about one sixth of a Saturnian year, enough time for the spacecraft to have observed seasonal changes in the planet, its moons and sunlight's angle on the dramatic rings.
Cassini passed through a gap in the rings as it entered orbit on June 30, 2004. It finished its prime mission in 2008 and continues to use its 12 instruments in an extended mission that includes extensive further studies of the moons Titan and Enceladus.