Jupiter spends almost all of its 2011-2012 apparition in Aries, substantially north of the celestial equator. This is good news for northern observers, who have seen this magnificent planet fairly low in the sky for the past six years.

Jupiter is reasonably well-placed for telescopic observing from June 2010 through March 2011. At the beginning of this period, Jupiter is visible only around dawn, but by September the king of planets is fairly high in the sky by midnight or earlier.

Virtually any telescope will show Jupiter's four Galilean moons and their interesting interactions with the planet or its shadow. During the course of every revolution, Io, Europa, and Ganymede pass in front of and then behind Jupiter’s disk, and Callisto also crosses the disk during this apparition.

For the convenience of telescopic observers, we are making available a list of Jupiter's satellite phenomena from June 2011 through March 2012 to supplement the monthly lists that usually (but not always) appear in Sky & Telescope. The list is in the form of a 20-page PDF, so you'll need a free copy of Adobe Reader software to open it and print it.

Phenomena of Jupiter's Moons, June 2011 - March 2012

For a graphic overview of the moons' motions, download one of our printable single-page PDFs. Click below for the desired month.

June 2011
July 2011
August 2011
September 2011
October 2011
November 2011

You can also run our Javascript utility to view the positions of Jupiter's moons at any moment.

Jupiter's famous Great Red Spot (GRS) is much harder to spot than the Galilean moons. Although it's quite large, the low contrast of the GRS can make it hard to see unless Jupiter is quite high above the horizon and the astronomical seeing is quite good. In addition, you need a reasonably big telescope (preferably at least 6 inches of aperture) with good optical quality.

But most important of all, you can only see the GRS when it's on the side of Jupiter that's facing Earth. And it's only reasonably easy to see within about an hour of the time that it transits, passing halfway across Jupiter's disk during each 9-hour and 55-minute rotation.

You can use our Javascript utility to find predicted times of GRS transits, or cllick here for a printable table of predicted GRS transits during the 2011-2012 apparition.