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December 30: Catch Mercury, quick
Our attention this evening is on Jupiter as the year comes to a close with a transit of the icy moon Europa across the cloud tops, trailing behind its dark shadow. Jupiter is approaching opposition, with the time between shadow and moon transits dwindling quickly over the next week and a half.
By 8 P.M. local time, Jupiter is nearly 30° high in the east, dominating the constellation Gemini at its opposition magnitude of –2.7. Europa’s shadow kicks things off at 9:01 P.M. EST as it slips onto the southeastern limb. Europa is alone to Jupiter’s east, while Io, Callisto, and Ganymede lie west of Jupiter, in that order from closest to farthest.
Europa follows its shadow onto the disk 28 minutes later, and both are visible together crossing in front of the gas giant for more than two hours. Europa’s shadow disappears just minutes before midnight EST, while Europa slides away from the southwestern limb nearly half an hour later, as the Central time zone is getting ready to ring in 2026.
Sunrise: 7:22 A.M.
Sunset: 4:45 P.M.
Moonrise: 1:47 P.M.
Moonset: 4:28 A.M.
Moon Phase: Waxing gibbous (92%)
*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.
