Published: December 17, 2004
This image taken by the Voyager 2 spacecraft of Saturn's A-ring shows the thin F-ring bracketed by its two shepherding satellites.
Because the inner moon revolves around the planet slightly faster than the outer one, the satellites lap each other every 25 days.
This picture was taken August 15, 1981, when Voyager 2 was 10.5 million kilometers (6.6 million miles) from Saturn. At that instant, the
shepherds were less than 1,800 km. (1,100 mi.) apart; they passed each other about two hours later.