Last night I had the pleasure to visit Mauro, a friend of mine and an amateur astronomer. Mauro owns a 24" dobson telescope with a mirror crafted by the superb hands of Romano Zen, the same who made my own 16". The precision of the optics of Romano is legendary, and as far as my limited capabilities allow me to judge, his reputation is entirely deserved. With my dobson scope I have been able, in nights of lucky seeing, to discern details on Jupiter of the order of half an arcsecond in angular extension. And with Mauro's 24"...

We had met to only observe Saturn -in fact the location and timing says it all: instead of dark moonless nights in the remotest sites in the eastern Italian Alps, we were in the mid of his garden, not far from the city lights of Mirano and Mestre. The moon was close to full. We usually chase faint galaxies, but not this time -Saturn these days is displaying very nice and unusual atmospheric activity, and with large telescopes it is possible to study these detailed features.

Clouds prevented us from exploiting a good part of the evening, but the planet was seen for a few lucky minutes both at the start and at the end of the observing session. The amount of detail that a perfectly crafted and well collimated 24" telescope, if thermally in equilibrium and with a good atmospheric seeing, is astounding. I have picked up from here a recent image taken by a Japanese amateur, Teruaki Kumamori, to describe what I could see.


All of the detail you can see here could be seen yesterday through the Ethos eyepieces of Mauro. In particular: all the zoning and banding on the disk; the three main rings (a,b,c) with the Cassini division; their shadows on the planet and the shadow of the planet on the rings; the white oval near the north pole; and in general, the eyepiece view at 380x magnification was less fuzzy than that of the image!

I am looking forward to Jupiter in October now...