Given clear skies, everyone with a decent backyard telescope should be able to view Jupiter’s moons, even on this moonlit night. In their outward order from Jupiter, these four major moons are Io, Europa, Ganymede and Callisto.
First, find Jupiter with the unaided eye. That shouldn’t be too difficult because this dazzling world beams much more brightly than any star. At mid-northern latitudes – as in North America, Europe and Asia – Jupiter lords over the south to southeast sky at nightfall and early evening, shining to the east (left) of the waxing gibbous moon. As seen from the southern hemisphere, Jupiter appears to the right of the moon.
Image credit: FlyingSinger
Jupiter climbs highest in the sky around 9 p.m. Thereafter, Jupiter slowly sinks westward. But Jupiter stays up late all thourgh December, not to set in the west till well after midnight.
Start with low power on the telescope because it’s easier to get a sharper focus. Jupiter’s moons appear as pinpoints of light on nearly the same plane. Now and again, a moon might be “missing” because these moons routinely swing behind and in front of Jupiter.
Image credit: NASA
As seen from North America this evening, Jupiter’s four moons appear in this order, going from east to west: Ganymede, Callisto, Io and Europa. Ganymede, Callisto and Io shine to the east of Jupiter, and Europa to the west.
Watch the moons of Jupiter move around their parent planet all through December.