Lunar sketch 4 of 12: Riccioli

Hi Aubrey,

Many thanks for your your message. Those details about Giovanni RIccioli are amazing. What an interesting life Riccioli had!

In terms of the feature, I was not sure whether I had the correct name. I did search for it in Rukl's book, but the feature that I observed (the darkened line running from Riccioli G to Lohrmann) was not named, so I went to the a digital Moon atlas I have on the PC, but again it was not listed. So I then went to the internet and discovered a good resource, so I must have made the mistake at that stage. Here is the image I worked from:
www.lpi.usra.edu/resources/lunar_orbiter...s/aimg/iv_168_h3.jpg

I would never think of you bursting my bubble, rather I think of you expanding it by sharing your knowledge of things astronomical. So, there is absolutely no need to apologise.

Kindest regards,

Darren.

Thank you for this clarification, Darren.

That Lunar Orbiter is an excellent image.
However sadly It does not show the dark grey line which clearly runs from Lohrmann to Riccioli G in Rukl’s and your sketch.
How weird is that?
Rimae Hevelius is shown alright.
Rimae Riccioli is shown too.
As you well know, my friend Darren, Rukl shows Rimae Hevelius on Map 28.
But if you have the eyes of a lynx, (indirect pun intended)you will see the last smidgen of it on Map 39. Rimae Riccioli is fully shown on Map 39.  
But no label is given for our strange grey line.
And it most certainly is a very prominent feature.
Certainly more research is required.
But is it available to us? 
Although I have never observed this feature I have completely full confidence you have nailed it astoundingly well.
And once again, you certainly have produced an excellent sketch.
I wonder when you get the opportunity to sketch Riccioli and its surrounding rimae in the distant future; what will your contribution look like then?
So keep up the good work, Darren!

Now when are we going to have clear skies again?
Blessings to all for Easter!
How I’m longing to devour my white Easter egg on Sunday!

Kind regards,  Aubrey. 

Hi Aubrey, 

Very many thanks for your message. Yeah, I was stumped when trying to find a name for what I saw. During the process I also found that this image  en.wikipedia.org/wiki/Grimaldi_(crater)#...oli_-_LROC_-_WAC.JPG but I was keen to use a more reliable source. Hence, the Lunar Orbiter. Between the two of these, I settled on the feature being Rimae Hevelius, but I was certainly not confident. Maybe it was the shadow cast by the mountainous / hilly region west of RImae Hevelius??? One thing I'm sure of though, is that those five smaller craters that are aligned in an arc were on the western side of the dark line /shadow. 

I suppose this is part of the reason why I like amateur astronomy so much: there's always something to learn / figure out, and someone who is equally if not more keen to contribute to the conversation.

Hopefully, I'll get another look at the feature some time soon.

Clear skies,

Darren.