Jupiter Meets Saturn: A Red Spotted Great Conjunction

Explanation: It was time for their close-up . Two days ago Jupiter and Saturn passed a tenth of a degree from each other in what is known a Great Conjunction . Although the two planets pass each other on the sky every 20 years, this was the closest pass in nearly four centuries. Taken early in day of the Great Conjunction , the featured multiple-exposure combination captures not only both giant planets in a single frame, but also Jupiter's four largest moons (left to right) Callisto , Ganymede , Io , and Europa -- and Saturn's largest moon Titan . If you look very closely, the clear Chilescope image even captures Jupiter's Great Red Spot . The now-separating planets can still be seen remarkably close -- within about a degree -- as they set just after the Sun , toward the west, each night for the remainder of the year.

Gallery: Notable images of the Great Conjunction submitted to APOD