The Sky Today on Monday, August 24: Iapetus at eastern elongation

Iapetus reaches its greatest eastern elongation from Saturn; although dim, see if you can spot the two-toned moon this morning. | Published: August 24, 2026 Iapetus is faint and sits far from Saturn today, but see if you can spot — or image — it as it reaches greatest eastern elongation. East is left and north is up in this view. Only moons brighter than about 12th magnitude are shown here; note their positions may be different if you’re observing at a different time. Credit: Stellarium/Oleg Pluton Looking for a sky event this week? Check out our full Sky This Week column. August 23: Double star Zeta Coronae Borealis This morning’s observation is a challenge, but if you’ve got a large scope or have some astroimaging experience, it’s one you’ll want to try. Saturn’s moon Iapetus has a two-toned surface, with one hemisphere much brighter than the other. Iapetus is also tidally locked to Saturn — as it orbits, it slowly rotates so that the same side always faces its parent planet. But from our point of view here on Earth, we get to see the changing faces of the moon as it turns in time with its orbital motion. At western elongation, when it reaches its farthest point west of the ringed planet, its brighter hemisphere is turned earthward and it is at its brightest, around magnitude 10. On the other side of its orbit, at eastern elongation, its darker side faces us and the moon plunges to 12th magnitude. Today, Iapetus reaches eastern elongation, when it is at its faintest. That already makes it harder than usual to spot, but the difficulty is increased by its large distance from Saturn as well. You’ll find it some 9.4’ east of the planet. Because it is both faint and far from Saturn, it will be challenging to spot visually, but dark skies and a large telescope will aid your efforts. It should show up on astrophotos, too, so give that a try if you’ve got the setup. Sunrise: 6:20 A.M.Sunset: 7:44 P.M.Moonrise: 6:06 P.M.Moonset: 2:29 A.M.Moon Phase: Waxing gibbous (91%)*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.