Just checked Mercury's rotation with CDC and Stellarium. When zoomed in, they seem to have the same mapping on Mercury in the same place (but no place names, of course!). So I guess I can be confident that the surface features they show are correlated to the real features on the planet. Cross referencing it back to an actual map with place names, (
http://quickmap.actgate.com/msgr_pub..._quickmap.html) and the Melown Map (
https://www.melown.com/mercury/) it looks like Caloris Planitia is in the right place, so maybe it's possible?
Aparrently it has a smoother topography than the surrounding areas, but according to the Melown map, it's *brighter than the surrounding area, not darker, which is how the ACT quickmap displays it. So that's inconclusive. And then the angle of the light may make a difference too, I suppose.
But as Clive pointed out, on the day in question the planet would have been about 8.4" across, with the Caloris Planita subtending about 2". With an 8" scope in inconsistent seeing, how likely is that kind of resolution given a theoretical resolution of 0.58"?
Sorry to flog this to death, but I'm fascinated by the idea that there may be some detail to be found on Mercury in amateur scopes. I'd never really spent too much time with Mercury because I thought there wasn't much to be seen, but if there is, that would be really cool!
Anyone else willing to have a go and see if they get the same results?Though I notice Caloris Planitia is rotating away from the limb now and into full sunlight, but perhaps that doesn't matter if it's purely albedo?
I'll try another night with my other scope (16") to rule out the optics, but tonight is a typical Melbourne white-out.
Markus