The Sky Today on Saturday, September 12: Dione skims Saturn’s pole

Dione crosses Saturn’s north pole, projecting its shadow onto the cloud tops as Tethys disappears into the planet’s shadow. | Published: September 12, 2026 Early on Sept. 12, Dione is preparing to skim Saturn’s north pole as Tethys is about to disappear into the planet’s shadow. Mimas, although shown, is 13th magnitude and too faint for many scopes. Note that Iapetus is some 2' north of Saturn at this time, outside this field of view. Credit: Astronomy: Roen Kelly Looking for a sky event this week? Check out our full Sky This Week column. September 11: Visit the Deer Lick Group Saturn dominates the southern sky in the early hours after midnight. It’s the brightest point of light here, standing some 50° high around 2 A.M. local daylight time. In addition to its biggest and brightest moon, mid-8th-magnitude Titan, 10th-magnitude Rhea, Tethys, and Dione are also often visible through a telescope, hugging the planet as they orbit closer in than Titan. Dione skims Saturn’s north pole early this morning starting around 2:55 A.M. EDT (the 12th in all U.S. time zones except Pacific, where it is just before midnight, late on the 11th). The moon is preceded by its small shadow, which appears on Saturn’s northeastern limb just after 2 A.M. EDT. Dione itself tracks over the north pole for about 40 minutes, before moving off to the west around 3:35 A.M. EDT. Shortly before Dione’s transit starts, look near the southwestern limb of Saturn to find Tethys approaching from the west. It disappears before it ever meets the limb around 2:10 A.M. EDT, when it passes into Saturn’s long, dark shadow, which extends beyond the planet to the southwest. During this series of events, Rhea is visible to the planet’s west with Titan beyond it, far to the west. Sunrise: 6:38 A.M.Sunset: 7:14 P.M.Moonrise: 8:17 A.M.Moonset: 7:47 P.M.Moon Phase: Waxing crescent (5%)*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location. Alison Klesman is senior editor of Astronomy magazine. She holds a Ph.D. in astronomy and has studied a variety of topics, from minor planets to supermassive black holes.