Titan casts a shadow on the planet Saturn
Titan casts a shadow on Saturn
Titan, Saturn’s largest moon, cast a shadow on Saturn as it orbited the planet on May 31, 2025. EarthSky’s friend Robert Lunsford captured the remarkable image above showing Titan’s shadow on Saturn. And that faint dot at the 10 o’clock position is Titan.
While shadow transits of the Galilean satellites at Jupiter are common, they are not as frequent at Saturn. In fact, they only occur about every 15 years. But luckily, right now, conditions to witness Titan’s shadow on Saturn are favorable.
According to Sky and Telescope:
Titan transits occur only during the relatively brief time Earth and Saturn both lie nearly on the same plane, which coincides with when the rings appear approximately edge-on.
In March, Saturn passed between Earth and the sun, so at the moment, its rings appear nearly edge-on to us on Earth. Saturn is ascending in the morning sky, and its rings are tilted less than four degrees. Consequently, the rings are less prominent, so shadows and details on the planet’s disk are easier to see.
More upcoming shadow transits on Saturn
You can see more Titan shadow transits through October. The dates are listed here.
Rhea, Saturn’s second largest moon, orbits closer to Saturn, so it transits the planet more frequently. You can see Rhea through telescopes of eight inches (20 cm) or larger.
Check Stellarium.org for possible shadow transits of Saturn’s moons from your location.
About Saturn’s largest moon
Titan is the second largest moon in our solar system, after Jupiter’s Ganymede. And it is Saturn’s largest moon. Its diameter is 3,200 miles (5,150 kilometers), which means it is larger than the planet Mercury. Titan shines at 8.4 magnitude, so you’ll need a telescope to see it.
Titan is the only moon in our solar system with a dense atmosphere. From telescopes on Earth, it appears 0.8 arcseconds wide. And yes, that’s tiny, considering one degree of sky is equal to your pinky finger held at arm’s length. Furthermore, it takes 60 arcminutes to make up one degree, and 60 arcseconds to make up one arcminute.
Bottom line: Right now, Saturn’s rings appear almost edge-on to us, and you can observe shadow transits of some of its moons. Here’s an image of the shadow of its largest moon, Titan, cast on Saturn’s cloud tops.
Weird! Titan’s atmosphere is wobbling like a gyroscope
Read more: Frigid Titan has soaring, bubbling clouds with unusual rains
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