Iapetus Moon Visible Near Saturn on Thursday, October 22

Shining at 11th magnitude on October 22, Saturn’s two-toned moon Iapetus is currently passing south of the ringed planet following superior conjunction, offering observers a view with a telescope, according to Astronomy magazine senior editor Alison Klesman.

On October 22, Iapetus sits just past superior conjunction, positioned south of Saturn. Saturn’s unusual moon Iapetus orbits the planet on a wide path that takes nearly 80 days to complete, as reported by Astronomy. During its orbit, the satellite slowly rotates in synchrony, causing it to brighten and fade by up to two magnitudes depending on which hemisphere faces Earth.

Telescopic Tracking of Iapetus

Iapetus lies 1.7’ south-southeast of Saturn, shining at 11th magnitude and appearing fainter than the other four moons. Because its orbit takes it far from the planet and leaves it relatively faint, Iapetus is easiest to locate during superior and inferior conjunctions, making tonight an ideal time to track it down.

Saturn is well-positioned for viewing soon after darkness falls, reaching a height of roughly 30° above the eastern horizon by 8 P.M. local daylight time. Through a telescope, observers can easily view the southern side of the planet’s rings. Bright Titan, Saturn’s largest moon, shines at mid-8th magnitude just 1.6’ east of the planet. Meanwhile, Tethys, Rhea, and Dione glow around 10th magnitude closer to the ringed world. Around 8 P.M. CDT, Dione is located east of Saturn, while Tethys and Rhea sit to the west.

Observational Timeline and Lunar Phase

The Moon appears as a waxing gibbous at an illumination of 89 percent, measured at 10 P.M. local time from the same location. Times for sunrise, sunset, moonrise, and moonset are recorded from 40° N 90° W. Sunrise occurs at 7:18 A.M., while sunset takes place at 6:10 P.M. Moonrise is set for 4:18 P.M., with moonset following at 3:20 A.M.