The cloudy skies that often plague amateur astronomers smiled on astrophotographer Steve Bellavia on the morning of July 18, 2025. They parted just in time, giving him a chance to image a fairly rare occurrence.
From his home in Smithfield, Virginia, Steve photographed the shadow of Saturn’s moon Titan transiting the face of the planet.
Image credit: Steve Bellavia
Titan shadow transits occur in groups, with each group spaced about 15 years apart. Five more shadow transits will happen this year - with the next occurring on August 3 (see chart below for dates and times).
“Going outside at 2 a.m. and seeing clouds — with some clear spaces — caused a little anxiety, but it was also exciting,” Steve said. “I had polar aligned the mount earlier in the evening, so I started by pointing the telescope to Saturn and focusing before the transit began.”
He imaged using an Explore Scientific FirstLight 152 mm Maksutov-Cassegrain telescope.
Watching the image stream onto his computer screen, he saw the ringed planet shaking in the atmosphere and disappearing behind clouds from time to time.
“At first, it seemed I wasn't going to get great data,” he said. “Around 3 a.m., I could see the shadow on the limb of Saturn.
“I started recording videos and alternated with just observing, using SharpCap's Live Planetary Stacking. I couldn't believe how prominent the shadow was, with Titan itself also visible.”
Around 4 a.m., the seeing improved.
“Saturn, Titan, and its shadow were really crisp.” That’s when he captured three minutes of video that he later processed into a finished image.
Around 4:30 a.m., a wall of clouds covered Saturn and most of the sky, signaling the end of the imaging session. He packed up his gear.
"I'm glad I got up and set up the Explore Scientific 152 mm Maksutov-Cassegrain,” he said.
With more opportunities to see other transits, he’s considering simply observing next time, using the FirstLight telescope and an eyepiece from his collection of Explore Scientific gear.
Now, if only the clouds will smile on him again.
WANT TO SEE IT FOR YOURSELF?
Although Titan's current transit series is halfway done, there are still five opportunities in 2025 for astronomy enthusiasts to try to catch this fairly rare celestial sight. The dates and times for each upcoming occurrence are shown below. It's important to note that during the October 6 appearance, the full shadow only appears on the planet mid-transit so there will be limited opportunity to wait for better seeing conditions or cloud clearing. After October 6, the next time to catch this event will come in 2040.
ABOUT THE IMAGE:
Steve Bellavia captured the transit of Titan's shadow using an Explore Scientific FirstLight 152 mm Maksutov-Cassegrain telescope, with focal extenders bringing the focal length to 2,370 mm.
He used a ZWO ASI 183MC Pro (not cooled) camera and an IDAS UV-IR cut filter.
He recorded two minutes of SER video at 40-millisecond exposures (25 fps), with the gain set to 320. The setup was mounted on a Sky-Watcher EQ6-R Pro using EQMOD software. The imaging session ran from 4:01 a.m. to 4:03 a.m. on July 18.
He used the best 40 percent of the 3,000 frames extracted from the video—about 1,200 images. These were registered and stacked in AutoStakkert.
Post-processing included wavelet deconvolution and de-noising in AstroSurface, followed by tonal contrast adjustments in Canon Digital Photo Professional.
He reported that clouds came and went but offered enough clear windows to get the shot he wanted. The air was slightly damp, with the temperature at approximately 15°C (59°F).
He rated the transparency as 7 out of 10 and the seeing as 3 out of 5.
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