Hitchhiker's Guide to Rukl Chart 2

Pythagoras (David North <d _at_ timocharis.com>)
Pythagoris is a well-formed crater with a nearly perfect double central peak. Complex collapse terracing could be seen well one day short of the full moon, particularly on the east side. Nearby Anaximander made a bleak plain, flat and blasted, as a mordant contrast to the nearly textbook perfection of Pythagoris (somehow appropriate).

Pythagoras can offer one of those rare views where you can see a crater's interior ledges as if you were looking at it while standing on a peak on the opposite rim. This angle is most likely to happen as we approach the full moon, and most opportune at the north and south limbs (where, curiously, Pythagoras is found...) Curiously, this good angle is the result of a libration that causes *greater* rather than lesser foreshortening (moving Pythagoras closer to the limb).

Pythagoras (Akkana)
Over at the north end of the terminator and on the limb, Pythagoras' central peak was throwing a nice shadow. The area south of Pythagoras is also interesting: see discussion under chart 8.
J. Herschel (David North <d _at_ timocharis.com>)
J. Herschel, in "The Hour Of The Long Shadows," is almost as scintillating as Sinus Iridum at its best. A vastly underrated view. Philolaus is also impressive, but seriously upstaged.

On Independance Day, 1998, on the eastern edge of J. Herschel, a curious "chimney" was spotted by Wm Phelps. Though nothing particularly high shows up on Rukls charts, and the Air Force charts show the entire rim at the same altitude, this looked like the famous "Devil's Rock" sticking up from the inner rim of the crater. I argued that it must be some illusion of light angles, in part because it was so much brighter than the surrounding rim. But last night, July 5, I looked at the area under different light and noted that the shadow from this now less-obvious feature was much longer than other parts of the rim. I think he's found something quite different there, and more observation and research will be required...

J. Herschel (Matt Tarlach <tarlach _at_ earthlink.net>)
3/9/98: Starting north of Sinus Iridum, the large walled plain of Herschel stood out plainly. I was able to detect at least 4 craters on the floor, only one of which really showed a bowl shape. There was also an bold, dark shadow on the wall of Herschel where it meets Anaximander. It looked like a deep, steeply walled valley joining the two features.

[The following day] I revisited J. Herschel, to see how it appeared under different lighting conditions. The dark valley reaching towards Anaximander, which yesterday I had taken to be a shadow effect, actually seems to exist! I see it as a neat cleft in the wall of J. Herschel, with the valley extending directly away from the center of that crater. It may end before the Anaximander ring-wall; I did not see a clear break there as I did at the Herschel end. There is no sign that the valley extends onto the floor of Herschel. The floor of the valley appears darker than the surrounding material. Wilkins (in _The Moon_, with Patrick Moore, 1961) drew a small crater on the wall of J. Herschel near the position of this "cleft"; perhaps that's what I'm seeing. In any case with 70mm this area appears to me very different than as mapped by Rukl.

J. Herschel (Bill Arnett)
I had a nice look this evening at the lunar crater J. Herschel. It was just past the terminator with the entire rim and floor illuminated. But what was interesting was that there was a dark shadow all the way around the inside of the rim. It appears to be a depression on the inner side of the rim. Or perhaps the entire floor is raised in a dome shape. There is also a not very prominent central peak. I've never seen a crater quite like that before. But it does make sense physically, I guess; the process that makes central peaks might also raise the entire floor. If it solidified more quickly than usual it might look like this.
J. Herschel (David North <d _at_ timocharis.com>)
[In response to Bill wondering if the floor is domed] I believe it's large enough that the curvature of the moon is significant in "doming" the floor; many of the larger walled plains have this characteristic.

Not that JH isn't weird; it seems every time I look at it some strange feature shows up.

I believe it was JH that William Phelps spotted that weird peak on last month, as well.

J. Herschel (Bill Arnett)
em>[In response to David's curvature comments] ... but that would affect the rim wall as well. The depression around the rim was clearly there all around.
South (JRF <freeman _at_ netcom.com>)
Way up north, I noticed a big rough-floored plain northwest of Sinus Iridum, and wondered what it was. Following the craters Bianchini, Foucault, and Harpalus across Mare Frigoris revealed that this northerly feature was named South. East and a bit north, the larger plain, J. Herschel, was prominent, and twin craters Anaximenes and Philolaus, with lots of structured rough terrain around and between them, made an easy landmark.
area around South (David North <d _at_ timocharis.com>)
Tonight's oddity was a "square" formed by the walls of South, J. Hershell, Mare Frigoris, and the plain between Babbage and Anaximander. In the light of last night, it looked like an almost perfectly square plateau with the crater Robinson smack in the middle ...

But the weirder thing is the crater South, which I (of all people) had never even noticed before. Its appearance is also prety much square, but it's nearly invisible even in low light! How it got named at all I'll never know.

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