On the evening of 6 August, 1998, while sitting in the illuminated living room a friend's house in Oakland, California, I happened to look at the nearly full Moon through a closed window -- a single sheet of glass -- and was struck by how much lunar detail was visible to the naked eye. The experience reminded me of the conjecture that perhaps the most such detail is seen when bright lights are around, so that the observer's pupils are not nearly as wide as they become in deeper darkness: The idea is, that the eye as a whole is not very well corrected, so stopping it down is likely to improve imaging, as long as there is enough light, which there certainly is for the Moon's desert landscape under the noonday sun.

The night of the 7th provided better observing; some of the local group (that's amateur astronomers, not galaxies) were partying in a house in Los Gatos, California. The full Moon was well-placed for observing from the back yard as it crossed the meridian, and I had brought Refractor Red so that I could double-check the locations and identities of anything I might see. I did the checking after the fact, in the interest of eliminating bias, though I of course know the Moon's surface tolerably from memory.

The major maria were easy: I could see Mares Crisium, Nectaris, Fecunditatis, Tranquillitatis, Serenitatis, Frigoris, Imbrium, Nubium, and Humorum, as well as the much larger Oceanus Procellarum. The region of Mares Vaporum and Insularum, and of Sinii Aestuum and Medii, was resolved enough to see these features as well, though I can never remember which is which. The great mountain masses of the Jura, Alps, Caucasus, and Apennines were easy albedo features.

And there was a lot of smaller detail. I could see Sinus Roris, (selenographic) west of the Jura and northwest of Oceanus Procellarum, and could sense Sinus Iridum as a dark indentation in the northern boundary of Mare Imbrium. The bright albedo features of the inner ejecta blankets of craters Copernicus, Kepler, and Aristarchus, were easily visible. More difficult was a lower contrast blur that encompassed the merged ejecta blankets of Archimedes, Aristillus, and Autolycus. The uplands between Mares Nubium and Humorum showed shape, though there are no named features there on the scale of what I was resolving. Perhaps the most difficult feature that I could hold steadily was Lacus Excellentiae, which many of you may not recognize because it is a new name, not accepted by the I.A.U. till 1976. It is a rather irregularly bounded patch of maria centered at about 36 S, 43 W, more or less containing the small crater Clausius.

Furthermore, I could see the flooded central basin of Grimaldi, just (Selenographic) west of the western edge of Oceanus Procellarum. The projected size of this dark patch is roughly 70 by 110 Km, and it is surrounded by brighter landscape, so as to stand out in high contrast. I have logged Grimaldi as "suspected" before, but on this night there was no doubt, I could keep the tiny dark fleck in sight for seconds at a time. (It is interesting that I could not hold it steadily -- with my 1x2 or 1x3 "telescope", seeing was certainly not a problem. This particular pop-in-and-out effect must stem from physiology of vision.)

Dawes's limit for a clear aperture of two or three millimeters is an arc-minute or somewhat less, though a magnification of only 1x might not be enough to show all such detail. In round figures, the Moon is 30 arc-minutes and 3000 Km across, so in principle, the human eye might be able to see lunar features as tiny as 100 Km, or perhaps a bit less, the more so if they are high in contrast, like a bright spot against dark material or vice-versa. I was observing with my glasses on, and they were clean. My current prescription is pretty good, and my vision usually corrects to about 20/15. What fun to push my observing skills to their limits without a telescope!

Yet in one way the experience was a failure. After nearly an hour of intense staring at the full Moon, my teeth and fingernails were in their normal condition (I won't tell you what that is), my ears remained rounded, and I found myself in possession of no unexpected patches of fur. I don't believe my behavior had changed, either, yet I must suspend my own judgement on that matter -- after all, I might not know -- and my fellow party-goers were generally in a state where they were unlikely to have noticed any difference.