English: Cassini sails low over the surface of Iapetus on approach to its close encounter with the enigmatic moon on Sept. 10, 2007. Its flight takes it over the rugged, mountainous ridge along the moon's equator, where ancient, impact battered peaks -- some topping 10 kilometers (6 miles) in height -- are seen rising over the horizon and slipping beneath the spacecraft as it flies. Frames used in this movie were acquired with the Cassini wide-angle camera on Sept. 10, 2007, as the intrepid robot soared past Iapetus (1,468 kilometers, or 912 miles across), within a few thousand kilometers of the surface. Additional simulated images were inserted between the Cassini images in this movie in order to smooth the appearance of the movement, a scheme called interpolation.