Jovian Dual-Shadow Transit of October 31, 2011

Remarkable was the dual-shadow transit on October 24. But, there is yet another and unfortunately the final dual-shadow transit of Jupiter in 2011. October 31 will bring us one more "astronomical morsel" and this one will be presumably about the same as the last: Io will transit just beneath the waistline of Jupiter, and Ganymede at the exact bottom of the king of the planets. Both of the shadows will be cast on the planet for only sixteen minutes, from 18:10 to 18:26 UT. This will be during the day for Washington DC, at approximately 1:10 to 1:26 EDT. Although this is rather sad, the eastern world will be able to witness the last Jovian dual-transit for the great year of 2011. A comprehensive photo shoot (courtesy of The Transits Page) is shown at the end of this article. Below is a picture of the Jovian moons at 00:00 UT on October 31, 2011, or at 8:00 October 30, for us here in EDT.

Image Credit: Transits Page; Text entered by AstronomicalEventsCalendar

Callisto beautifully rests on top of the planet, as it's orbit appears to be above the planet, we must remember that these orbits are three dimensional - and that since Jupiter is titled towards us, it looks like Callisto orbits above. Sense Perception! Concerning the transit, you can see Io and Ganymede - Ganymede will swoop down and catch up to Io (they are not actually that far apart in the two-dimension scale, becasue of their orbits, but they appear to be far apart). The dual-transit itself will start at 17:46 UT and end at 18:22 UT, lasting only 36 minutes. If you can remember, this is very shorter than the October 24 transit.The next picture below concerns itself right before the transit - at 16:00 UT. Ganymede and Io are now very noticeable together.

Image Credit: The Transits Page; Text entered by AstronomicalEventsCalendar

If you're wondering what a Jovian dual-sahdow transit is? Look no further - Here, we can clarify the terms of dual-shadow transit, and dual-transit, becasue both can happen at the same time - the October 24 and 31 transits are great examples of these (among others). A dual-shadow transit occurs when two shadows of moons travel across the surface of Jupiter together (and yes this can also happen on any other planet with two or more moons, etc.), and then, when the two moons travel together, it is called a dual-transit. (The difference is just either the shadow or moon), but both have to cross Jupiter (or any other planet, etc.) at the same time. You can read more about Jovian transits in our last transit: October 24.

-all pictures below are credit The Transit's Page, Galilean Moons Simulator; text entered by myself-

Another object to note is the conjunction of Io and Ganymede again, but the next day:
2011-Nov-01 05:19 Conjunction of Io and Ganymede [144.0" W; 21.7" S].

2011-Oct-31 15:12 Conjunction of Io and Ganymede [44.7" E; 13.1" S]

2011-Oct-31 16:13 Transit Ingress of Io (All satellites no more visible to the east of Jupiter)
2011-Oct-31 16:18 Shadow Transit Ingress of Io
2011-Oct-31 17:18 Inferior conjunction of Io
(2011-Oct-31 17:45 Conjunction of Callisto and Europa [204.4" E; 38.1" S])*
2011-Oct-31 17:46 Transit Ingress of Ganymede (Double Transit Begin)
2011-Oct-31 18:10 Shadow Transit Ingress of Ganymede (Double Shadow Transit Begin)
2011-Oct-31 18:22 Transit Egress of Io (Double Transit End)
2011-Oct-31 18:26 Shadow Transit Egress of Io (Double Shadow Transit End)
2011-Oct-31 18:30 Inferior conjunction of Ganymede
2011-Oct-31 19:09 Transit Egress of Ganymede
2011-Oct-31 19:24 Shadow Transit Egress of Ganymede

*Object of Note!
(with thanks to the Galilean Moons Simulator)

Results of the October 31, 2011 Jovian Dual Transit

An other amazing spectacle in solar-system astronomy! We must thank again the moons for such a wonderful show - as Io and Ganymede transited this last October 31, 2011. We here in America could not view this event as proficiently as we could have hoped to, but scattered simulations were found all over the web, reminding us of what did occur. Although I could find no pictures of this last transit, (it was very fortunate that I did the last!) here are some computer simulations from all over the web for us to see what did happen. 

"After having such a prolific season of simultaneous Jovian dual-transits last May-June, it will be hard to accept the fact that we have only two more this 2011 season: October 24, 2011 and October 31, 2011. Each transits are an exact week apart (although times differ) and both are dual-shadow transits. Io and Ganymede both partake in each event, as their orbits must be aligned perfectly just for this week." Read more at the link above. (Basic insight of what happened).

31 October 18.23 UT

Here's a simulation from WinJUPOS of what it will look like at 18:15

Below is a picture computed (simulated) by Celestia software. You can see Ganymede and Io as the light blobs, and their shadows cast on the planet. If you would to see the picture clearer, you may click on it for higher resolution.

Although these are not the most high quality images available, they do beautifully illustrate the beauty of this transit. So, just to say - I will hopefully be receiving the 2012 Galilean moons calendar soon - so until next year....

Credit: NASA