Hitchhiker's Guide to Rukl Chart 50

Darwin (JRF <freeman _at_ netcom.com>)

Disintegrating crater with several associated rilles. The latter form an interesting contrast with the great Sirsalis Rille, which extends down from Rukl chart 39.

Darwin (David North <d _at_ timocharis.com>)

The Sirsallis rille passes right by Darwin, who had a fat western lip tonight. The bulge in its rim was at precisely the angle for the light to exaggerate it into something resembling The Garden Of the Gods in Colorado Springs. Some aspect of Darwin is always interesting when it is near the terminator. (See also chart 39.)

Mare Orientale (Akkana)

A flooded plain, normally on the far side of the moon and only visible from earth during favorable librations.

6/20/97: Tracing the profile along the terminator was particularly interesting: the flatness of Orientale, then a steep drop to the valley to the south, then two rises where the concentric mountain ranges stood in relief against the unlit limb, and a pair of long dark streaks extending further northward, perhaps ejecta from the event which formed Orientale.

Two craters stood out prominently off the north edge of Orientale, both with huge central mountains nearly filling the crater ("central peak" doesn't do justice to these peaks). Rukl is difficult to read for "far side" features, but I might guess that the crater to the southwest of Grimaldi and inside the concentric rings of mountains may have been Maunder (on Rukl's Libration Zone VII map), or possibly Kopff; it stands out very prominently, and Rukl gives no hint of the central peak being so huge in comparison to the size of the crater. The one to the northwest could have been Schluter.

Orientale can be an interesting area even when several days off the terminator, if the libration is favorable. On June 10-11, '98, with the terminator several days past, I made a sketch of all the landmarks I could see in the VX102, to see how far into the Orientale basin I was seeing. Not much of the mare itself, as it turned out.

Orientale (David North <d _at_ timocharis.com>)

The most favorable libration for Mare Orientale offered a very good look at the Cordillera and Rook mountains, and quite possibly a bit of a glance at the Mare floor, though that's uncertain... it may have been a bit of Lacus Veris, or whatever. Really rotten seeing, but not so bad I couldn't get clean kills on Schluter, Shaler and some other "out there" craters.

But all that is secondary to the sheer size and form of Mare Orientale, which requires nothing more than good binos, really. This libration was good enough to get a very full feel for the roundness and the look of the shock that would be required to form such a structure; it's just plain awesome.