- 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.