# Is it possible for a septuple eclipse to happen on Saturn considering there are 7 moons capable of eclipsing the Sun?

The reason quadruple eclipses can never happen on Jupiter is because of the 1:2:4 orbital resonance between Io, Europa, and Ganymede. As far as I know this isn't a problem for Saturn's moons.

From Wikipedia's Solar eclipses on Saturn:

Seven of Saturn's satellites – Janus, Mimas, Enceladus, Tethys, Rhea, Dione and Titan – are large enough and near enough to eclipse or occult the Sun, or in other words to cast an umbra on Saturn.

Of the 7 listed above, Mimas and Tethys are in a 2:1 orbital resonance and so are Enceladus and Dione, however that doesn't stop either pair (or all 4 together) from eclipsing Saturn at the same time.

So, in theory, it is possible for all 7 moons to more or less line up together. Does this mean that during eclipse season on Saturn, there can be a septuple eclipse? If so, when is the next one going to happen?

• Interesting question! What exactly is a septuple eclipse? Does it just mean that shadows of seven moons appear somewhere on Saturn's disk at the same time? They don't have to all fall on the same location, right?
– uhoh
May 27 '20 at 7:36
• Yes, like you said, it means 7 simultaneous eclipses happening at once and thus 7 shadows somewhere on Saturn's disk. May 27 '20 at 11:43
• So from one Saturnian observer's location, one eclipse and 6 transits. May 27 '20 at 14:03
• I suspect there’s something keeping it from happening… Anyhow, an interesting read, though not directly about that, is Mathematical Astronomy Morsels, by Jean Meeus, in which he addresses the possibility of having all planets lined up. He quickly concludes that it’s impossible. I suppose the same for Saturn’s seven “eclipsing” moons. Nov 21 '20 at 17:52

The possibility that the Sun is along the same line is $$\displaystyle \frac { \text {(angular size of the Sun as seen from Saturn)}°} {360°} = \frac {0.05} {360}$$; let’s be generous and round it off to 1:10,000.