The moon and Saturn tonightApril 19, 2010
It was almost freakishly clear and calm here in Claremont this evening. My friend and fellow blogger Andy Farke came over and we spent some time looking up. First target was the waxing crescent moon. Here in town, the seeing is often so bad that at anything over 100x, the image looks like it is under a rippling sheet of water. But tonight we were able to push on to 240x with no problems. I’d say the effects of seeing (atmospheric turbulence) didn’t start to be noticeable until 120x and even at 240x it wasn’t a dealbreaker.
Here’s Mare Nectaris and vicinity (click for the larger, unlabeled version). The line of craters formed by Theophilus, Cyrillus, and Catharina is an easy catch in binoculars at this phase. The Altai Scarp is an immense range of cliffs, hundreds of miles long. Mare Nectaris formed as a multi-ringed impact basin, much like the Chicxulub crater from the “dinosaur-killer” asteroid, and the Altai Scarp is the largest surviving stretch of one of the outer rings.
We had a look at Mars, which was a well-defined disc with hints–and only hints–of detail. I suspected the ice cap from time to time, but couldn’t convince myself that I’d really seen it, as opposed to just thinking the disc looked lighter where I know the ice cap ought to be. Still, a whole ‘nuther planet, y’know? Give me a telescope and a world to point it at and I get a little giddy.
The real treat of the evening was Saturn. At 120x it was crisp and jewel-like, but at 240x it was simply astounding. I have never seen so much detail in one of my own telescopes. The photo is by far my best ever for Saturn, but it just doesn’t do it justice, not by a long shot. The whole planet was striped with pastel bands, and we could clearly see the gap between the rings and the planet. The dark band stretching across the disc is the shadow of the rings. Three moons shone out proudly to the left of the rings; Stellarium informs me that they were Dione, Rhea, and Titan, from inward to out. After Andy left I even caught little Enceladus–she of the geysers–between Dione and the rings.
I also cruised over to the globular cluster M3 and it was very nice, a contained explosion of stars. It looked better than I’ve ever seen it, which is saying something since the moon was out. Most DSOs don’t suffer unduly from bad seeing since they are extended and dim to begin with, but globs do. I’m half-tempted to haul out the scope again and have a look at M13, which ought to be up now, but I have to sleep sometime. Good night, and clear skies.