Jupiter's Galilean Moons
Using this application it is possible to compute and visualize the positions of Io, Europa, Ganymede, Callisto - also known as the Galilean Satellites of Jupiter - in real time or at any given time in the past and in the future.

Upcoming Galilean Moons Phenomena
The following table lists all the upcoming events involving Jupiter's Galilean moons in the next 7 days.
Date | Local Time | Satellite | Event |
---|---|---|---|
May 24 | 15:55 | Io | End Transit |
May 24 | 16:26 | Io | End Shadow Transit |
May 25 | 10:50 | Io | Begin Occultation |
May 25 | 13:35 | Io | End Eclipse |
May 25 | 17:24 | Europa | Begin Transit |
May 25 | 18:23 | Europa | Begin Shadow Transit |
May 25 | 20:02 | Europa | End Transit |
May 25 | 21:02 | Europa | End Shadow Transit |
May 26 | 07:32 | Ganimede | Begin Occultation |
May 26 | 08:11 | Io | Begin Transit |
May 26 | 08:41 | Io | Begin Shadow Transit |
May 26 | 10:25 | Io | End Transit |
May 26 | 10:55 | Io | End Shadow Transit |
May 26 | 12:20 | Ganimede | End Eclipse |
May 27 | 05:21 | Io | Begin Occultation |
May 27 | 08:03 | Io | End Eclipse |
May 27 | 12:32 | Europa | Begin Occultation |
May 27 | 16:09 | Europa | End Eclipse |
May 28 | 02:42 | Io | Begin Transit |
May 28 | 03:09 | Io | Begin Shadow Transit |
May 28 | 04:56 | Io | End Transit |
May 28 | 05:24 | Io | End Shadow Transit |
May 28 | 23:51 | Io | Begin Occultation |
May 29 | 02:32 | Io | End Eclipse |
May 29 | 06:48 | Europa | Begin Transit |
May 29 | 07:41 | Europa | Begin Shadow Transit |
May 29 | 09:27 | Europa | End Transit |
May 29 | 10:20 | Europa | End Shadow Transit |
May 29 | 21:12 | Io | Begin Transit |
May 29 | 21:38 | Io | Begin Shadow Transit |
May 29 | 21:53 | Ganimede | Begin Transit |
May 29 | 23:26 | Io | End Transit |
May 29 | 23:37 | Ganimede | Begin Shadow Transit |
May 29 | 23:37 | Unknown | Unknown |
May 29 | 23:52 | Io | End Shadow Transit |
May 29 | 23:52 | Unknown | Unknown |
May 30 | 00:42 | Ganimede | End Transit |
May 30 | 02:27 | Ganimede | End Shadow Transit |
May 30 | 18:22 | Io | Begin Occultation |
May 30 | 21:00 | Io | End Eclipse |
May 31 | 01:57 | Europa | Begin Occultation |
May 31 | 05:28 | Europa | End Eclipse |
May 31 | 15:43 | Io | Begin Transit |
May 31 | 16:07 | Io | Begin Shadow Transit |
May 31 | 17:57 | Io | End Transit |
May 31 | 18:21 | Io | End Shadow Transit |
Events are defined as follows:
- Occultation: the satellite is moving behind Jupiter from our perspective, so the satellite hides when the occultation begins and reappears when the occultation ends.
- Eclipse: the satellite is moving inside Jupiter's shadow. Sunlight is blocked by Jupiter and the satellite, no longer directly illuminated, is seen to disappear when the eclipse starts and reappear then the eclipse ends.
- Transit: the satellite is moving in front of Jupiter's disk. Depending on the conditions, the satellite can sometimes be difficult to see during a transit, appearing as slightly lighter or darker than Jupiter's clouds.
- Shadow Transit: the shadow of the satellite is moving on Jupiter's disk. The shadow typically appears as a dark circular spot clearly visible on Jupiter's clouds. This event, as seen from jupiter, is analogous to a solar eclipse.
Credits
The algorithms to compute the positions of the Galilean Moons used in this application are based on the jsaa project (Javascript Implementation of Astronomical Algorithms) which, in turn, is based on algorithms published by Jean Meeus on his Astronomical Algorithms book.