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April 28: Ganymede passes through Jupiter’s shadow
This evening, you can spot the planet Jupiter just a Full Moon’s width from the magnitude 3.5 star Wasat, also cataloged as Delta (δ) Geminorum.
As the sky grows dark this evening after sunset Gemini is still relatively high in the west, with Jupiter the brightest light within its boundaries. Jupiter is located just to the upper right of Wasat, and both are visible together in a telescope eyepiece or within a binocular field of view.
By the time East Coast observers can observe the planet easily with a telescope, only three of its Galilean moons are visible: Io to the west, and Callisto (closer) and Ganymede to the east. Europa is now passing behind the planet in an occultation similar to Ganymede’s journey last night, which won’t end until shortly after 12:15 A.M. MDT on April 30, when Europa finally pops out of the planet’s shadow to Jupiter’s east. Observers in the Mountain and Pacific time zones can catch the reappearance.
Before then, though, Callisto overtakes Ganymede to the far east of the planet. Visible to those in the western two-thirds of the U.S., Callisto passes due north of Ganymede around 12:15 A.M. CDT on April 30, after which the two moons exchange places and Callisto lies farther from Jupiter than Ganymede.
Sunrise: 6:02 A.M.
Sunset: 7:53 P.M.
Moonrise: 6:14 P.M.
Moonset: 4:46 A.M.
Moon Phase: Waxing gibbous (97%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
