Jupiter Moon Dance Last Night

Started by 1953, 10/02/2010 04:34PM
Posted 10/02/2010 04:34PM Opening Post
The sky around here last nigh was really rather clear & stable allowing Jupiter to really shine...pun intended.

The moons were putting on a real show at around 8:00 to 11:00 PM eastern US time. One was transiting the planets face, casting a shadow, while the other was maybe 40-50 seconds off of the limb, midway between a pole and the equator. There was a very pronounced 3D effect with the off-limb moon and planet when using the binoviewer. It got even more 3D looking when the transiting moon started to emerge from Jupiters face and stand against space. And just as the one moon was exiting transit, the shadow of the other moon started to appear as a little bite mark right at the top (bottom?) of the planets pole. The whole thing was thrilling actually.

Another thing I've noticed, especially last year when the view from here was along the plane of Jupiters moons orbit, is the moons disks are more distinctly circular when they are close together. Interesting visual effect.

Jeff

"Don't sweat the petty things and don't pet the sweaty things" 8O
Posted 10/02/2010 07:55PM #1
Hi Jeff--

Sounds like a great view--you gotta love those multiple transit events. I've also been riveted to Jupiter on several nights the past couple of weeks, although I was fogged out last night. Had great transits of Europa and Io on successive nights, and the seeing has been quite good, lots of detail. By the way, I think you saw Io transiting and Callisto off the limb, according to Cartes du Ciel, about 6 pm PDT (1 am UTC)? Your circular moon comment is intriguing--may I ask what are you observing with? I recently noticed that adding a paracorr to my 10" f/5 made the moons more circular across the field, while previously I saw them as disks near the center of field only. But you seem to be suggesting an optical/perception effect. Perhaps having them close together makes their relative sizes stand out...

-George

George Golitzin