Moon, 20th April 2021

Hi all

Using my 120mm refractor, stepped down to 60mm, I got a small observing session on the moon, before the beautiful clouds rolled in.
Plato was first up, the saw tooth shadows of the crater rim were cast beautifully across the flat and featureless floor of the crater.  To the south, there was one needle point of shadow that raced three quarters of the way across towards the opposite wall.  It would be interesting to see what this section of the crater rim would look like from the surface, I am thinking something along the lines of a Mont Blanc.

The Archimedes Mountains, just south of Archimedes, are a pair of curved raised plateaus with a curved valley running between the pair.

Between the crater Bancroft and Archimedes, is a raised ridge of material, it runs along the lunar floor at the foot of the uprising lands that forms the crater Archimedes.  There is a second ridge of material, of a similar colour, that runs up the crater slope of Archimedes, the two ridges are joined at one end, giving a V shape, looking like an old cut throat razor.  The ridge running up the crater wall appears to continue over the crater rim and onto the crater floor, is this merely a line of sight effect or something else?

Feuillee and Beer craters a pair of equal sized twins sitting in the barrenness of the Mare Imbrium, they give the appearance of a pair of dark eyes looking back.

There is a large wrinkle ridge running from the dark side of Mare Imbrium into the light.  It emerges north of Eratosthenes, runs halfway across Imbrium and curves back, running south of Pico and Montes Tenerife before slipping back into darkness.  I can find no name for this feature, does anyone know its name?

Going back to 120mm, I attempted to see the central fault that runs down the length of the Alpine Valley, I employed my maximum magnification, X281, but by now the clouds were starting to slip over the moon and soon thickened to obscure everything.  Has anyone observed this fault?

Paul

I'm sorry I'm the bearer of bad news, Paul. 
I do see your large wrinkle ridge on Mare Imbrium on Map 11 in Antonin Rukl's Atlas of the Moon.
But it has no name - which is surprising - as it is very prominent. 

And also I have never observed the narrow rille in Vallis Alpes. 
I have tried! 

However I do thank you for another wonderful report on Luna!

By the way, I will be observing the 9.7 day old Moon in Leo later on if the skies stay clear. 

Best regards from Aubrey. 

Thank you for your observing notes on the Moon. Could I ask how you step down your 120mm refractor to 60mm and why you do this when observing the moon ?
Thank you.

Hi

Stepping down the aperture is just a matter of making a mask to fit over the aperture of your scope.  They are simple to construct using cardboard, I use cereal boxes, cut a circle the same diameter as your dew shield, then an inner circle the diameter you wish.  I have 50mm, 60mm, 80mm and 100mm masks, giving me the equivalent of 5 scopes.  Attach the disk to your dew shield by cutting strips of cardboard that fit around the circumference of your dew shield and join both strips and disk together with whatever works, I use duct tape, they are ugly, but effective.
The glare of the moon can be overwhelming, especially as the phase approaches full, stepping down the aperture reduces the glare considerably and makes viewing more comfortable.  Longer focal length scopes are generally better for lunar observing.  You do not diminish what you can see with a smaller aperture.

Hope this explains somewhat.

Paul

Hi Aubrey.

I have Charles Woods atlas of the moon and there is no mention of a name.  I have searched the web and came up blank. This is a large feature when you see that really small ridges and faults get names, to ignore one this large is really strange.

Maybe I should contact the IAU and get them to name it after me.

Paul

Hi Paul,

Very many thanks for another  fine Moon report. I always enjoy reading your vivid descriptions of lunar features. And I agree with your description of Feuillee and Beer - they definitely look like a pair of eyes.

Also, I second the motion of naming the crater after you; you could go with 'Paul', but 'Lunartic' is more apt name 

Clear skies,

Darren.