A Jupiter Almanac

Jupiter spends its 2014-2015 apparition near the Cancer/Leo border, well north of the celestial equator. This is good news for northern observers, who can see Jupiter for a long time and quite high in the sky.

Jupiter is reasonably well-placed for telescopic observing from September 2014 through June 2015. At the beginning of this period, Jupiter is visible only around dawn, but by December the king of planets is fairly high in the sky by midnight or earlier.

Jupiter with Moons
Jupiter with three of its Galilean satellites: Io, Europa, and Callistor (left to right), recorded on March 16, 2003.
Virtually any telescope will show Jupiter's four Galilean moons and their interesting interactions with the planet or its shadow. For the convenience of telescopic observers, we are making available a list of Jupiter's satellite phenomena through December 2015 to supplement the monthly lists that usually (but not always) appear in Sky & Telescope.

Phenomena of Jupiter's Moons in 2015
Phenomena of Jupiter's Moons in 2016

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

In late 2014 and most of 2015, the orbits of Jupiter’s moons are almost perfectly edge-on to the Sun and Earth. As a result, the moons eclipse and occult one another. These “mutual phenomena” are fascinating to watch, and digital imaging technology now allows observers to image them and time them as never before. Predictions of all these events are given in the online Astronomical Almanac.

The Great Red Spot can only be seen when it's near the center of Jupiter's rapidly rotating disk.
S&T: Sean Walker
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.