Here are the four bright "Galilean" moons of Jupiter -- Io, Europa, Ganymede and Callisto -- and their shadows. It also shows the position of Jupiter's "great red spot" (GRS).
North is up; west is right (binocular/Newtonian view, not refractor).
Or you can set a date explicitly: Recalculating ...
Delay: 100 milliseconds
Show events for hours.
New for 2013! Now you can predict future events, see eclipses, and I improved the graphics so it's more obvious when moons are emerging from behind Jupiter. Please report any bugs you find.
Times are approximate. There are lots of different models for Jupiter's moons, and they all seem to give slightly different results, especially for shadow events and eclipses. Start observing ten or fifteen minutes early if you want to be sure of catching something.
I use this app on Android with the help of my
For older Java phones, Miguel Moreto has adapted this code for a neat mobile phone app called Mobile Jupiter.