Saturday, October 22, 2011

December 27, 2011 Dual-Shadow Transit

According to the "Robert Ferguson Observatory," they state in their 2011 Observing highlights, that there will be a dual-shadow transit of Europa and Ganymede on December 27, 2011. Although I do recommend their observing highlights to those who would like to know, their event is incorrect. They have:

  • Tuesday, 12/27/2011 - Dbl Sh Tr Jup - Time: 18:00
    • Double shadow transit of Jupiter:
      Transit of Europa is already in progress at sunset.
      06:00p Nautical twilight ends
      06:05p Ganymede's shadow begins transit
      06:32p Astro twilight ends
      07:44p Io is occulted by Jupiter
      07:51p Europa's shadow begins transit
      07:52p Europa transit ends
      07:55p Ganymede's shadow transit ends
      10:15p Europa's shadow transit ends
      11:07p Io reappears from eclipse

Although I do not wish to refute this prediction, after checking the Galilean moons simulator, they're prediction is wrong. Ganymede does transit and Io does eclipse, but Europa is just too far away from Ganymede for dual-shadow transit. Without making any advanced Judgments, this may occur, but maybe if viewed from a different angle on the earth.

Computer Simulation of Galilean moons provided by the Galilean Moons Simulator, Text Inserted by AstronomicalEventsCalendar

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Credit: NASA