Astronomy Picture of the Day

Explanation: Every 15 years or so,Saturn's rings are tilted edge-on to our line of sight.As the bright, beautiful ring system grows narrower and fainter itbecomes increasingly difficult to see for denizens ofplanet Earth.But it does provide the opportunity to watch transits of Saturn's moonsand their dark shadows across the ringed gas giant's still bright disk.Of course Saturn's largestmoon Titanis the easiest to spot in transit.In this telescopic snapshot from July 18,Titan itself is at the upperleft, casting a round dark shadow on Saturn's bandedcloudtops above the narrow rings.In factTitan's transit seasonis in full swing now with shadow transitsevery 16 days corresponding to the moon's orbital period.Its final shadow transit will be on October 6, though Titan's pale diskwill continue to cross in front ofSaturn as seen from telescopes on planet Earth every 16 daysthrough January 25, 2026.