Moon, 12/1/2006

by Marek Cichanski

Over the previous few days of clear weather, I'd been watching the moon as it waxed fuller and fuller, and I realized that the "Moon Season" was closer than I thought.

It wasn't until I read Rukl several years ago, as well as some of Dave North's SJAA Ephemeris columns, that I realized the seasonality of lunar observing. Certain phases of the moon ride high at certain times of year, and they ride low at other times of the year. I'd grown accustomed to thinking of spring as the 'moon season', and it generally is, but it occurred to me the other day that PARTS of the 'moon season' begin as early as early December. At this time of year, when the terminator is in the 'far west', the moon is north of the celestial equator, around Pisces and Ares, and thus gets pretty high in the sky.

Aha!, I said, that means that I can get a good look at the Aristarchus Plateau, the Marius Hills, and Mare Humorum tonight!

So, out came the gear. Having a G-11 to put the M603 on was a very nice treat. Nice and stable. The scope is an f/10 Mak-Cass, and I put my Denk II binoviewer on, using an Orion SCT diagonal. I didn't use my WO/Denk dedicated diagonal with the PowerSwitch, because I didn't like hanging everything off of some little set screws. So, I put the 2" 'dovetail' adapter on the Denk II, and put it in the diagonal with no OCSs. By racking the focus nearly to one end of its travel, I could achieve focus. Cool. Nice view. The 24 Panoptics gave me a full-disc view, and the 9mm type 6 Naglers gave me a nice high-power view. Plenty good enough, and not much need to change focuse, unlike the PowerSwitch.

Initially the seeing was good enough for a 24 Pan full-disc view, but not really good enough to use the 9mm Naglers. I always like to see how much detail I can spot, even at low magnification. Call me the "Mag-Down King". Here are my notes from the full-disc survey:

"Starting in the north, Philolaus and John Herschel are prominent. Harpalus is prominent, in western Mare Frigoris. There are two small massifs - one equant, one elongated NE-SW - flanking a line between Harpalus and Foucault. They're nice little mountain masses, I'm a bit surprised they don't have names.

Sinus Iridum is prominent, but it's not as dramatically lit as it as last night. The "hummocky ejecta" in which it sits looks nice and hummocky, especially to the north and west of Sinus Iridum.

Hey, here's something I hadn't really noticed before... there appear to be narrow, linear clefts trending NW (more like WNW) across the hummocky material. One of them passes between Mairan and Sharp. Another starts at the NW-most point of Sinus Iridum. Rukl doesn't show them. I checked Byrne (his recent 'Lunar Orbiter Photographic Atlas of the Near Side of the Moon'), but Byrne doesn't quite show this area.

God help me, my nemeses the Gruithuisen domes are visible. Gonna have to tilt at THAT particular windmill at some point tonight.

Nice subtle wrinkle ridges on the mare between the G. domes and the Aristarchus plateau.

Montes Harbinger look very nice tonight, standing proud of the mare along with the north rim of the flooded crater Prinz. Oh lord, I have to go after stuff like the rimae around Prinz. Chained to the wheel again...

The floor of Krieger is still pretty much in shadow, but I can see the craterlet Krieger B at this magnification... neat!

Aristarchus, of course, is prominent, with the plateau just coming in to view. No Vallis Schroteri yet. Both the brightly-lit inner W rim and the outer E rim glacis have a "two-level-terraced" look.

Marius is RIGHT on the terminator, only its outer northeast rim visible, and this only a ghostly grey. The portion of the Marius Hills to the north of it is DRAMATICALLY lit.

(With a little imagination, I can almost see Dick Gordon and Joe Engle swooping down out of the darkness onto those hills, circa 1973. If that had happened, it would have been an Apollo landing that just might have made it into my conscious memory, as Skylab barely did. It would be back there in that jumbled landscape of my earliest memories, circa 1973-1974. The memory would be hanging out back there with the memories of other early-70s news items... "What did the President know, and when did he know it?"... "I am not a crook"... "Our long national nightmare is over"...)

The ray systems from Copernicus, Kepler, and Tycho are very prominent tonight. Lovely. Kepler makes a nice stout punch-hole in the surface of the Oceanus Procellarum.

The subtle ridges in the mare south of Marius are beautifully lit. The most prominent of these ridges heads due south from Marius, and only its east side is lit... it's RIGHT on the terminator. There are other ridges, even more subtle, feathering out to the SSE. I'm almost surprised that they don't have names, but maybe they're less prominent at steeper illumination.

The "terra/mare" contact around Letronne is just exquisite. Subtle, low-relief, gentle albedo contrast, but it's SO there! What a great example of a 'mappable contact'. The 'terra' material includes a nice NW-pointing triangular arm between Letronne and Billy/Hansteen/Mons Hansteen. Shows nicely on Rukl 40.

Mons Hansteen is looking big and chunky in this light, kind of like that big peak in the Haemus Mountains.

The floor of Billy is still in shadow, and there's a peak just east of the outer east rim that's casting a shadow on the outer E rim and ACROSS the crater onto the inner west rim. Neat! A "shadow ray".

The floor of Gassendi looks nice and detailed, even though the light is getting a little high.

Man, from Billy south past Mersenius and to Schickard is almost indescribably complex... a veritable chaos of craters, domes, massifs, and small mare patches. A 'titan's pandemonium' in this light.

You could call this the "Night of the Double Craters", what with Hainzel and Schiller both being nicely lit.

The Schiller / Zucchius basin rings are showing nicely. Okay, the seeing's getting good, time for the 9mm Naglers...

No joy on the Mons Gruithuisen Gamma summit crater. No big surprise there. I think I'm gonna have to use the Challenger for this sucker.

Can see some of the Rimae Prinz, but not everything depicted in Rukl.

It looks as though there's a faint graben running from the N end of Scheiner to the SE edge of Longomontanus. Hmm. It's not shown in Rukl. Aha! Byrne shows it on p. 60! Says that it's a ridge and furrow that's probably ejecta from the Schiller-Zucchius basin. Cool. And it's partially overlapped by Clavius ejecta."

After that, I wrapped up by going back to the full-disc view. I switched my iPod over to an audiobook of 2001 and listened to Heywood Floyd's journey from Space Station 1 to Clavius base. The full-disc view looked reasonably like the Lick photo towards which Kubrick's spacecraft falls, and it invoked childhood dreams of the moon. Hope I get to see that big, dirty-orange Ares V head that way soon. You go, bubbas. Swoop down out of that darkness from beyond that terminator and bring us some mantle xenoliths from the Marius Hills. I want me a thin section of one of those suckers.

Posted on sf-bay-tac Dec 03, 2006 13:29:06 PT
Converted by report.pm 1.4 Dec 12, 2006 20:22:43 PT