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Transit of Io

Started by [email protected], 10/09/2010 03:38PM
Posted 10/09/2010 03:38PM | Edited 10/09/2010 03:43PM Opening Post
Did anyone else view the transit of Io across the face of Jupiter last night? This observation was only the second moon/shadow transit I have seen and the only transit viewed through large aperture. It was really amazing to see the moon appear as a small bright pimple on the edge of Jupiter and slide across against the blackness of space and appear as a disc and not just a point of light. The dark defined shadow made for a real 3D effect to the whole scene. Maybe I am crazy but it seemed as if I could see some of the other moons in phases (half moon like)..that's not possible right with the sun behind us? I could also see size differences between the moons with Io appearing as the smallest. Am I crazy or is this possible through a 12.5" mirror? The sky was exceptional here in Quebec last night and one of the best nights I have had so far in my three years of observing. I have a permanent smile todaysmile

Mike


Posted 10/09/2010 04:39PM #1
Hi Mike:

Yes I saw it too and the 3D effect with the binoviewers was indeed pronounced. However, I saw the moon entering transit across the face of Jupiter. As it started transit it was extremely bright and could be easily followed across the face of Jupiter. Later, the shadow started as a bite on Jupiter's limb and that's when the 3D effect was most pronounced. The Skies were very steady last night which allowed me to use the full aperture of the 11" D&G. Normally, I use 7", 8.5" or 9.5" stops to better match the prevailing seeing and can only use the full aperture for lunar/planetary work a few times a year.

BTW, as I mentioned in a previous thread, as the moon approached the edge of Jupiter, I found it much easier to resolve as a disk, and especially easy as it was crossing Jupiters face.

And another BTW, don't forget Uranus, which is right next door. At 380X it was a very distinct and rather large disk. During moments of the steadiest seeing, which I guaged by the sharpness of the disk, I could make out a gradation of color and brightness across it's face.

Thrilling really.

Jeff

"Don't sweat the petty things and don't pet the sweaty things" 8O
Posted 10/11/2010 06:48PM | Edited 10/11/2010 06:49PM #2
Well I didn't see the transit of Io, but I did see an interesting phenomenon with Callisto. I was observing Jupiter with the 6" f/9 Starfire, on the morning of October 10 at 3:00 AM and saw Callisto sitting atop (North) of Jupiter with just a tiny gap between the planet and the moon. Callisto looked like a perfectly round dot at 200X in 6-7/10 seeing. According to Sky & Telescope, September was the last month for several years that Callisto will interact with the Planet and its shadow. Quite a sight.

Dom Q.
Posted 10/18/2010 11:53PM #3
Yeah Mike, that was a good one. smile
I was doing a new public star party (Heritage Starfest) in southern Utah that night
and the next, and folks really got a kick out of watching the transit.
At first I could only see the shadow, but was soon able to see Io itself,
as Jupiter climbed higher and the seeing conditions improved.
FYI, I was using a 14.5" Starmaster (Zambuto).
Between the transit and the comet, we had plenty of treats for our local crowd.
Linton