The simulator displays overview of Jovian system or closeup of Jupiter or any galilean satellite.
The simulator displays umbral shadows of satellites when any is transiting Jupiter.
If a satellite is eclipsed by Jupiter's umral shadow it is still displayed (if not occulted at the same time) but appears much fainter than if illuminated by Sun.
The simulator does not display mutual eclipses of galilean satellites.
Simulator uses ephemeris generated by NASA JPL's HORIZONS system so satellite's positions are as accurate as we know them. Shadows are however computed by approximations, and Great Red Spot longitude is optimized to fit over 2009 and 2010 and for other years there might be deviations from true position by several degrees.
Planetary and satellite's position is only know with high accuracy over limited period of time. Moreover, simulator uses large amounts of data downloaded from the HORIZONS system. Only years near the present offer one minute accuracy in order to save disk space and cover larger time interval.
If this option is chosen a saveable gif image will be displayed, otherwise simulation via html will be made. On some occasions html output has visibly better quality than gif generated. Thats why you might want to use this option only when you want do download certain simulation.
If this option is turned on, displayed positions will be updated every minute with the current ones. Works only with current time.
If this option is turned on, in top left corner will be listed information such as distance to target, its apparent diameter and so on. Your browser must support javascript.
Generally speaking it is intended to take an ever closer look of mutual occultations and very close conjunctions of satellites. Works only if a satellite is selected.
That's why satellite is being occulted at the selected time.
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The use of all images in other publications is freely permitted.
You can do so here.