drop = 2.3 / U.S., Europe April 17 / Callisto occults Ganymede / 9:27 – 9:37 p.m. drop = 2.5 / Hawaii April 13 / Io eclipses Europa / 9:29 – 9:33 p.m. All eclipses of Europa occur when that moon is close to the planet.Īpril 10 / Io eclipses Europa / 8:22 – 8:25 a.m. Events visible in the Americas are highlighted. To convert to CDT, subtract one hour MDT subtract 2 hours PDT subtract 3 hours AKDT subtract 4 hours and for UT, add 4 hours. I've included two diagrams showing Jupiter and its moons at the time of an event, but to determine which moon is which for the others, click on the Sky & Telescope Jupiter's Moons site. Stellariumįor a complete list of all remaining eclipses and occultations (even the impossible ones), stop by the British Astronomical Association's (BAA) Jovian moons mutual event pages - one for eclipses and another for occultations. There are several tables out there, but I've found these to be the most reliable. I = Io, II = Europa, III = Ganymede and IV = Callisto. View of Jupiter and moons during the eclipse of Europa by Io on April 13th. After May, it's a long 6 years to the next season opener. They're the best easy-to-see events for the remainder of Jupiter's apparition. That probably won't be necessary with the events I've listed below because they all involve fades of one full magnitude or more. You can judge brightness changes by comparing the moon undergoing eclipse or occultation to one that's not. Make sure your clock is set correctly and begin observing a good 5 minutes before an eclipse begins or 10 minutes before an occultation, so you can watch the two moons merge. From left: Io eclipsing Europa April 13th Callisto occulting Ganymede April 17th and another Io eclipse on April 20th. The eclipsed moon began at normal brightness, dropped a very obvious 2.4 magnitudes at deepest partial eclipse, and returned to normal all in the span of four minutes! Simulations of three fine upcoming mutual events. It was the deepest event of the entire season.Ī very nice eclipse of Europa by Io during the last mutual event series in September 2009.Ī week later on March 16th I was thrilled to see Ganymede pick on Europa again. "I saw an Europa total eclipse by Ganymede tonight, (a) remarkable event with the intense phase happening in a couple of minutes, including Europa completely disappearing." Europa, normally magnitude +5.3, faded by more than four magnitudes to +9.6 under Ganymede's shadow. WinJuposĪmateur astronomer Giorgio Rizzarelli of Italy was caught off-guard by the depth of an eclipse of Europa by Ganymede on the evening of March 9th: Simulation of the March 9th deep eclipse of Europa by Ganymede. A dip of at least a magnitude is much easier to detect and far more dramatic. You have to pay close attention and carefully compare the fading satellite's brightness with another nearby moon to convince yourself you're seeing it. Since the events last only a few minutes at most, the change is subtle. The eye can detect a drop of 0.5 magnitude during an eclipse or merger of two moons in a mutual occultation, but experience shows this is a lower limit. The current run began last September and ends in July. Now, as the four Galilean moons slowly break their neat alignment with us, deep events are becoming few and far between. Mutual event seasons occur every six years when the orbital plane of the four Galilean moons is edge-on with that of the Sun and Earth. April is really the last good month to catch the easy-to-see ones. Jupiter's moons will continue to occult and eclipse one another until the planet is lost in the solar glare this summer, but the average depth of the events diminishes with every week that goes by. The vagaries of weather and event times have limited my own opportunities to fewer than a handful. Maybe you've been fortunate and seen some of the more dramatic mutual occultations and eclipses of Jupiter's moons this season. See them soon or wait six more years! Mutual satellite events can occur in any of six ways, depending on slight differences in the moon's angular sizes and relative positions. Jupiter's four brightest moons continue to eclipse and occult one another, but time is running out.
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