The Sky Today on Sunday, November 8: Io and Callisto race across Jupiter

Small but speedy Io races the larger moon Callisto as the pair crosses in front of Jupiter early this morning. | Published: November 8, 2026 Io and Callisto are transiting Jupiter early on Nov. 8, with Io’s shadow visible on the cloud tops. Although Io’s transit begins after Callisto’s, the former will catch up with and overtake the latter by 3:30 a.m. EST. Credit: Astronomy: Roen Kelly Looking for a sky event this week? Check out our full Sky This Week column. November 7: Venus meets the Moon Rising with the stars of western Leo shortly before midnight, bright Jupiter and its Galilean moons put on a show early this morning, better visible the farther east you’re located. Jupiter is just under 5° northwest (to the upper right) of Regulus as they rise in the east. Fainter Mars stands roughly 3° above Jupiter. You’ll want your telescope trained on the gas giant soon after rising to catch the show, which begins at 1:29 A.M. EST as a shadow appears on the planet’s eastern limb. This is Io’s shadow — but don’t be fooled by the positions of the moons you see in your scope. The moon closest to Jupiter on the east is Callisto, while the moon just east of that is Io, whose shadow we see. Ganymede lies farthest east, while Europa is currently hidden behind the planet in an occultation. The latter appears from behind the eastern limb about 1:54 A.M. EST, not long before Callisto reaches the planet and begins a transit at 2:07 A.M. EST. Keep an eye on Io and Europa: Io passes north of Europa at 2:23 A.M. EST, then heads into its own transit about 2:42 A.M. EST. Now the race is on, as Io approaches and then catches up with Callisto as the two moons transit, passing Callisto and moving west of it within half an hour. The two moons and Io’s shadow continue to transit until 3:45 A.M. EST, when Io’s shadow leaves the western limb, and Io takes about an hour and a quarter longer before egress. Callisto continues trundling along, finally finishing its transit about 5:51 A.M. CST, with the sky now starting to brighten with twilight in the Midwest. Sunrise: 6:37 A.M.Sunset: 4:50 P.M.Moonrise: 6:07 A.M.Moonset: 4:08 P.M.Moon Phase: New*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. Alison Klesman is senior editor of Astronomy magazine. She holds a Ph.D. in astronomy and has studied a variety of topics, from minor planets to supermassive black holes.