Hitchhiker's Guide to Rukl Chart 31

Copernicus (JRF <freeman _at_ netcom.com>)

This magnificent feature is most people's choice for the most gee-whiz crater on the side of the Moon toward Earth. The walls are richly detailed, showing terracing on their inner surfaces, where wall material has slumped back toward the crater floor. Slumped landforms are common on Earth, too, notably where soil has crept and slid under the influence of heavy rain.

The crater floor has a complex of central peaks, with much additional detail, particularly toward the south. The ejecta blanket has overridden much of the original surface just outside the crater, and extends for hundreds of kilometers in a bright ray structure that is prominent at high sun angles.

Copernicus is visible to the naked eye, from Earth, as an albedo feature, when well illuminated. It is a "landmark" feature, easily recognized and useful for orientation.

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

July 14, 1997: The domes around Copernicus are showing well, along with all the other really spiffy detailed stuff (craterlets and tiny rilles) but my "new" observation for the night was mostly tonal ranges; the way the ejecta seems to have formed light and dark smatterings for such a great distance. More and more, it becomes apparent how violent that smack was when the crater was formed.

May, 1997: While perusing the rich field around Copernicus, appreciating the little craterlet lines and fine rille structures shot throughout, we started noticing the domes as showing particularly well... especially the group of five near Hortensius, one of which is a double dome with only one peak "cratered." We were easily able to spot the central craters in all of them (save the one that has none), so we went shopping -- and found another group showing well almost directly to the north.

In the process, we also noticed a few wrinkle ridges that seem to end in small craters, almost like a negative version of Rima Birt or Schroter's Valley. This may be coincidental, or it might be a feature of the Copernican topology. But another odd thing was these *enormous* domes in the area. One was a little north and west of Milchius, and shows well on the charts. The other, equally well defined, does not show on my charts: it was west and slightly north of Reinhold. This is interesting in that they are so low and usually (I presume) ill defined as to be a rare event; I wonder if anyone knows if the second large dome (probably about 25x35 miles) is charted anywhere? It was definitely pear shaped, with the narrow end to the south southwest.

The last weird feature of the night was a squarish island north of Copernicus, across the mountains, and directly west toward the terminator. It appears separated from the rest of the range, and distinctly square -- raised much like a dome, but peppered with all manner of blocks and marks as if it were somehow piled there as a rubbish heap. Odd, indeed.

Copernicus on the dark side (Randy Muller <71172.1234 _at_ compuserve.com>)

4/30/98 (young crescent moon): On the dark side of the moon [ ... ] Copernicus and its ray system was visible nearby. Using averted vision helped. The rays were very prominent.

Copernicus (ALPO)

See the Selected Areas Program page on Copernicus.

Copernicus and Rima Gay-Lussac (Robin Casady)

Rukl's atlas shows a snake-head at the southern tip of Rima Gay-Lussac. This I could not see. It appeared to go right into a promontory of Montes Carpatus. At the northern end, a bulge could be seen. Rukl's appears to show this as a small crater.
(<d _at_ timocharis.com> David North adds: In better conditions, I have seen the "cobra head Mark II" on that rille.)

A catena going out from Copernicus, and perpendicular to Rima Gay-Lussac, was easily seen, but only some of the craters could be resolved. Stadius was not easily distinguished, but the tiny craters in the area were quite evident.

Clavius showed lots of little craters in its interior. Longomontanus D looked like a single crater with an illuminated banana in the center. Only part of the inner rim could be seen.

Fauth and Reinhold (...Akkana)

Fauth and Fauth A make a tight figure-8 right next to Copernicus. Reinhold has an amazing 2-step terraced wall, with a prominent ghost crater, Reinhold B, right next to it.