The Moon and Jupiter 10 Dec 2024
Sky was looking clear so I set up about 19:30 MST. Plan was to just look at the Moon and then Jupiter. I used Solar System Alignment with Jupiter for the alignment target. I messed up and put the date in as Dec 12 instead of Dec 10! I didn't realize what I had done until later. GoTo was obviously off because of that, but tracking was good and I was able to scan over to the target,
Moon was at 77%, very bright, and was the first target for observation. Just after I got aligned and moved to the Moon a layer of cloud started moving in from the northwest. it eventually mostly obscured Jupiter. It kept moving SE and didn't affect the Moon.
I initially had the 32mm eyepiece in just to scan and look for interesting features that might catch my eye. I didn't have the Moon filter in to start, but it was so bright it left an after image in my eye when I looked away. I put the filter in to make it easier to look at. I started looking along the terminator and the rim of Montes Jura stood out. The terminator was cutting across the plain floor and just the tops of the peaks were illuminated. They showed up as an irregular bright white line in the dark beyond the terminator. I changed to the 17mm eyepiece to try for a better view. Seeing was fairly steady. The brilliance of the peaks of Montes Jura was astonishing to me. Very brilliant, surrounded by a sea of absolute black. Montes Recta and parts of Montes Tenerife were also brightly lit. That entire area sunward from the terminator was illuminated, but the light was still at a low enough angle that the peaks showed brighter than the surrounding Mare. There was enough shadow in the Montes to show texture. Craters Helicon and Le Verrier had deep black shadows in the bottom with the western rims illuminated inside. South of Montes Jura, there were scattered peaks on the dark side of the terminator that were highlighted.
Below are two sketches of the area. The one on black paper was done after After I came in based on my sketch at the eyepiece. It was a poor effort to catch the contrast in the light and dark areas. Also, you need to keep in mind that these sketches are based on what is seen in the eyepiece of an 8" Schmidt Cassegraine telescope (SCT) with a star diagonal. This means the view in the eyepiece is flipped left to right form what you would see with the naked eye.
In the sketch above, the scale in the eyepiece circle is off. The objects didn't fill that much of the field of view.
After sketching Montes Jura, I started scanning south along the terminator. There was a formation with a shape that caught my eye. I used the Sky and Telescope Mirror Image Field Map of The Moon (this was the first night since I had bought the map that I had a chance to use it, and it worked great). I identified it as Montes Raphaeus. The shape reminded me of braided bread rolls. The way the light was hitting it made it look like the shorter part had been wrapped over the longer main strand.
After making a rough sketch of that immediate area, I shifted to Jupiter. The four Gallilean moons were esily visible to the left of the planet in the eyepiece. With the 17mm eyepiece I could see the two major belts to the north and south of the equator. They seemed to have a very faint brownish hue. The equatorial region was quite a bit lighter but still had some hint of shading. There were two narrower bands just outside the two main bands that were almost white. Outside of those was a second colored band, lighter than the others but definitely a shade darker than the white areas. I didn't see the GRS. I tried using the 8mm Plossl but the seeing was just a little too unsteady for me to get a good focus.
A breeze came up that set the entire rig to shaking in the eyepiece, So I called it quits. The temperature when I went out was 31deg F. When I came in it was 29 F with 53% humidity, but I didn't experience any dew or frost.
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