Several nights ago, with the 9 day old moon only 20 or so degrees above the s.s.w. horizon, I attempted to observe any of the craterlets (or a hint of them) on Plato’s wonderfully smooth floor. It had been a hot day and, just after sundown, it was still pretty toasty. The atmosphere was slightly hazy/dirty and turbulence was present. There was also an expansive and wispy cloud right in front of the moon. Obviously, this was not a great night for attempting my goal, but I was off work the next day which gave me a whacky, “why the heck not?,” attitude.

Using my 114mm reflector — my second smallest scope — I slipped in a 24mm eyepiece and found the image to be surprisingly good (but what isn’t with a 1″ focal length EP?). Next I inserted a 12.5mm EP and the image still held up fairly well. Plato was now big enough to reveal its crisp, serrated rim. . .but no craterlets. Finally, using a 7.5mm EP, atmospheric issues became the limiting factor. I could still get a halfway decent glimpse of the crater in moments of better seeing, yet no craterlets were apparent. Had conditions been better, it didn’t seem impossible that my 6mm or 3.8mm eyepieces may have produced the illusive craterlets.

So I put it to you, what is the smallest aperture which you have successfully used to yield Plato’s craterlets?