Looking for a sky event this week? Check out our full Sky This Week column.
January 19: Where Messier started: M1
Comet 24P/Schaumasse is roughly 10th magnitude, visible using optics or in astrophotos of the sky. Rising shortly before local midnight, Schaumasse is best seen in the early-morning hours — and with no Moon in the sky, it’s a great time to look for it in southern Boötes, not far from the bright star Arcturus.
Let’s use that magnitude –0.1 luminary as our jumping-off point today. Around 4 A.M. local time, Arcturus is readily visible some 55° high in the east. Center your optics on this star, then drop about 9° south-southwest to land on Schaumasse.
Given the moonless sky, you might try observing a few nearby galaxies as well. Check out the chart above to help you find NGC 5363 and NGC 5248. Both sine at magnitude 10.2, roughly the same brightness as the comet. NGC 5363 is a lenticular galaxy in Virgo, located some 6.3° southwest of Schaumasse this morning. NGC 5248 is a spiral in Boötes, lying about 8° west of Schaumasse today. Consider the appearance of both galaxies relative to each other as well as the comet — how do they all compare?
Sunrise: 7:18 A.M.
Sunset: 5:05 P.M.
Moonrise: 8:33 A.M.
Moonset: 7:09 P.M.
Moon Phase: Waxing crescent (6%)
*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.
Ganymede transits the face of Jupiter on the morning of January 21, trailed by its large shadow. The event starts just before 4 A.M. EST on Wednesday, as Jupiter is slowly setting in the west for much of the U.S. (The planet is still high in the southwest for those on the Pacific Coast, who will have the best views of the entire transit.)
Jupiter hangs beneath the bright star Pollux in Gemini — in fact, the gas giant outshines the star, making it the brightest point of light in the Twins by far. Train your telescope on Jupiter and you’ll see that before the transit starts, all four Galilean moons are lined up on the planet’s eastern side. Callisto is farthest away, with Europa slightly closer, followed by Io; Ganymede sits closest to the planet’s southeastern limb. Ganymede begins to transit at 3:51 A.M. EST, moving from east to west across the large world’s face. It takes more than an hour for its shadow to appear, around 4:58 A.M. EST, as Ganymede is nearing the halfway point in its journey.
Ganymede’s transit ends shortly after 6 A.M. CST, with the planet only 5° high in the Midwest and only about an hour to go before sunrise there as well. The shadow finally disappears from Jupiter’s southwestern limb around 6:20 MST, visible only in the western half of the U.S. (and again, best seen from the West Coast).
