Europa Transit

by David Kingsley


Around 9:30 to 10:30 pm tonight the seeing was the steadiest I have had in Palo Alto for the last couple of weeks. Beautiful views of Europa's shadow ahead and the GRS near meridian. Very sharp detail on the moon. I was able to run magnification up to 350x or so on my 7 inch Starmaster Dob.

The seeing was steady enough that I went in search of the small channel that runs down the middle of the Alpine valley on the moon. I was able to make out part of this channel as an extremely fine white line running along about 40% the length of the valley. My sketch of this feature suggests I was only detecting that stetch of the channel that lies south of a major meader in the channel that is visible on Lunar Orbitor photos (chart 115-3).. The seeing got worse around 11 pm or so and I packed up.

I notice that the jet stream is currently far north of us (up by Seattle and Vancouver). That is supposed to help the seeing. Scope cooling itself is a huge factor in the steadiness of views. I continue to be impressed at how much a small fan on the back of my Dob can clean up unsteady images that i used to attribute to poor seeing.