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Various astronomical "shadow events" occur throughout the Solar System!  This month's more interesting ones are featured here.

SHADOW WORKS

Here we highlight the most awe-inspiring eclipses taking place in our Solar System.  We also set them up so that all you need to do is click on their links.  Don't forget that you can generate lists of Earth's, Jupiter's, Saturn's, Uranus's, Neptune's and even Pluto's eclipses, using CELESTIA's own built-in "Eclipse Finder."  You'll find it in the program's menu under "Navigation".

Unless noted otherwise, the events identified below are displayed as if viewed from Earth, their magnifications shown in parentheses at the lower right of CELESTIA's window.  Events involving more than one moon are often cyclical, so usually only the first example is given, and then the period of the cycle.

Remember: you can press the   M   key to toggle Moon Labels on and off .

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JUPITER

Jupiter is now in that part of its orbit where its equatorial plane, and the orbital planes of the four Galilean moons, are increasingly tilting with respect to the Sun.  While Io, Europa and Ganymede all produce solar eclipses each time they orbit Jupiter, this is not true of Callisto, whose increasingly tilting orbit has made it incapable of casting its shadow on Jupiter since last December.  It will not be able to cast its shadow on Jupiter again until 2013!

Five simultaneous solar eclipses (i.e. involving more than one major moon) occur on Jupiter this month, courtesy of Io and Europa.  Here are highlights of the 29 solar eclipses that Io, Europa and Ganymede spawn in May, as Jupiter's shadow now extends to the planet's west (right).

With the Galilean info below, it is easy to see why some events involving more than one moon repeat.  This info also lets you predict when events may recur.
Periods:
   Io:  1.769 days
   Europa:  3.551 days
   Ganymede:  7.155 days
   Callisto:  16.69 days
Resonances:
   Io & Europa: 2 to 1
   Io & Ganymede: 4 to 1
   Europa & Ganymede: 2 to 1

• May 2: Io, Ganymede and Europa appear near Jupiter; Europa enters Jupiter's shadow, then Io begins casting its own shadow  (1.6.x)   (1.4.1)
• May 4: Io follows Europa "in front of "Jupiter, both casting their shadows, though not at the same time  (1.6.x)   (1.4.1)
• May 5: Ganymede passes Io east of Jupiter and then goes on to cast its shadow as Europa appears to the west; hours later Io casts its shadow  (1.6.x)   (1.4.1)
• May 7: with Callisto to their east, Io again follows Europa "in front of" Jupiter both casting their shadows  (1.6.x)   (1.4.1)
• May 14: Io has "caught up" to Europa enough so both can cast their shadows on Jupiter at the same time; this is the first of 5 "simultaneous" solar eclipses this month that occur about 3½ days apart  (1.6.x)   (1.4.1)
• May 16: as Io approaches from the east, Ganymede, Europa and Callisto approach from the west; Ganymede and Europa enter Jupiter's shadow, but Callisto is too "high" to do so  (1.6.x)   (1.4.1)
• May 18: Io and Europa again cast their shadows on Jupiter at the same time  (1.6.x)   (1.4.1)
• May 25: Io, Europa and Callisto appear near Jupiter  (1.6.x)   (1.4.1)
• May 27: casting its shadow, Ganymede is less than one planet diameter from Jupiter, as Europa enters Jupiter's shadow  (1.6.x)   (1.4.1)

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SATURN

Like Jupiter, Saturn is now in that part of its orbit where its equatorial plane, as well as the orbital planes of its major equatorial moons, are all tilting more and more relative to the Sun.  So fewer and shorter eclipses will occur on the ringed planet for some time.  Rhea, Titan and Iapetus have not been able to cast shadows on Saturn since Oct 2010, Feb 2010 and Jun 2007 respectively.  They will not cast their shadows on Saturn again until Mar 2024, Oct 2024 and July 2022 respectively.  In addition, last month Dione cast its last shadow on Saturn until Jul 2023.

While CELESTIA 1.6.x shows the shadows of Titan, Rhea, Iapetus, Dione and Tethys, version 1.4.1 displays only the shadows of Titan, Rhea & Iapetus.  So, 1.6.x and 1.4.1 respectively show 16 and no solar eclipses on Saturn in May.  In addition, version 1.6.x reveals no double simultaneous solar eclipses this month, as only Tethys produces a solar eclipse on Saturn now for a dozen years!  Moreover, Tethys is casting its shadow further and further south, and before long it too will not be able to produce a solar eclipse on Saturn for some time.

To aid in your viewing, here are the periods of Saturn's major moons.  These do not exhibit the resonances that Jupiter's Galileans display.  Still, you can use this info to predict subsequent eclipses of a single moon.
   Tethys:  1.888 days
   Dione:  2.737 days
   Rhea:  4.518 days
   Titan:  15.95 days
   Iapetus:  79.33 days

• May 1: Tethys casts its shadow on Saturn, as it now does about every 2 days  (1.6.x only)

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URANUS, NEPTUNE & Dwarf Planet PLUTO

Neither Uranus nor Neptune will experience eclipses for decades.  Dwarf planet Pluto will experience no eclipses by Charon for about a century!

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