Javascript Jupiter

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).

The moon positions are set using Javascript, which is disabled in your browser. You'll need to turn it back on if you want to see the current position of Jupiter's moons.

I E G C I E G C I E G C GRS

Or you can set a date explicitly: Recalculating ...

Delay: 100 milliseconds

Show events for hours.

About Javascript Jupiter

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.

This is a re-implementation of my older Java Jupiter page using HTML, CSS and Javascript (and nicer graphics). It is Copyright © 2000 - 2013 by Akkana Peck, licensed under the GNU Public License v.2. Feel free to share it or modify it! If you do, I'd appreciate hearing about it, and a link back to my site.

I use this app on Android with the help of my WebClient wrapper app.
For older Java phones, Miguel Moreto has adapted this code for a neat mobile phone app called Mobile Jupiter.