Chris McKitterick (mckitterick) wrote,
Chris McKitterick

Astro-Image(s) of the Day: Saturn and Three Views of the Moon

Howdy! I took today's shots late last night, when Saturn was directly overhead and the Moon was a bit to its right. My goal was to photograph Saturn, but that didn't work out very well:

This shot does show that the rings are pretty much edge-on right now, and that's interesting, but the camera just doesn't know what to do with really bright objects. To the naked eye, I could differentiate the ring from the planet - like a very slight shadow on the globe below - and what appeared to be four of its moons. Titan was obvious and I thought for sure it would show up in the image, but its parent planet was so bright that it overwhelmed the light from its little coterie of worlds. I'll continue to play with this.

Oh, and I should mention: WINDY! Most shots were blurry due to wind. I really want an observatory ;-)

To take successful shots of the Moon, I used a masking technique to reduce the amount of light entering the telescope. My high-tech method included standing beside the tube and slowly moving my arm in front of the aperture to block up to about half the light. This took advantage of the 'scope's full resolution power (full width of the mirror) without its full light-gathering power. Shots I took without masking showed bright areas as washed-out and pixelated. The best shots seemed to be when I blocked most of the light by placing my arm (in a thick jacket) across the widest part of the aperture. Oh, and I was also using a polarizing filter set at its darkest (about 40%). This should give you a little idea of just how damned bright is the Moon through a 12" telescope. It's also a bit too long-focus to take full shots of the Moon: Note that only a small portion of the world shows up in each shot. That's without any magnification (no eyepiece), directly into the camera, and with the focal length shortened by 37% from using an f/6.3 focal reducer. Okay, the shots:

In this first photo, notice the two bright craters with what looks like stripes spreading out from them. Those are called rays, detritus from the impacts that created those craters. Also notice that some craters are dark and some are light; this has to do with what was going on geologically on the Moon at the time those craters formed. Really dark ones show melted rock that filled the craters from deep below, and bright ones are filled with Lunar dust. Even more dramatic are the vast maria, the huge dark areas rimmed by brighter walls. Yes, those are the remnants of massive craters that almost destroyed the world back in its earliest days.

This next one is all about showing off the rayed crater, Tycho. Imagine the energies involved in creating rays that span nearly half the globe!

Finally, this last shot is from the first set I took, which I like in that it shows the unlit edge of the world (nearly Full Moon during the photo-shoot) plus lots of contrasting-brightness craters and maria:

If you want to identify all the craters, I found a good map here:

Click the image to see the site.

Tags: astronomy, telescopes

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