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The Sea of Moisture through the Fog

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#1 frank5817



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Posted 17 September 2009 - 08:26 AM

Sea of Moisture through the Fog

One month ago (August 15) I began a sketch I was unable to complete due to interfering clouds and lucky for me early on the morning of September 13 with the moon at approximately the same phase, I completed the graphite sketch of most of the Mare Humorum basin (380 km.). This impact basin is a different shape and somewhat smaller in size than Mare Crisium (600 km.).
Research mapping data puts the age of this sea at about 3.9 billion years, a Nectarian period formation.
The floor is flooded over by a thick layer of basaltic lava especially over the central region. Additionally a number of large interesting craters ring the margins of this basin. At the southern edge (12 o’clock position in the sketch) you can see craters: Vitello, Lee and Doppelmayer. At the north edge (6 o’clock position) you can see crater Gassendi and on its rim Gassendi A.
The lighting on both occasions was excellent for viewing the lava ridges on the eastern side of the maria.
Both days were excellent for viewing a steady lunar image with a notable amount of fog on the second viewing morning.

Sketch was made over two observing sessions
For this sketch I used: white sketching paper 10”x 8”, HB, 4B, 6B graphite pencils, a blending stump and a plastic eraser and eraser shield. After scanning, Brightness was decreased (-2) and contrast increased (+2) using Microsoft Office Picture Manager.

Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241x
Dates: 8-15-2009, 9:30-10:25 UT; 9-13-2009, 10:00-11:10 UT
Temperature: 15° C (59° F), 16° C (61° F)
clear, calm, then cloudy the first day, Very humid both days, dense fog on the second day
Seeing: Antoniadi II-III
Colongitude 205.5°, 200.2°
Lunation 24.27 days, 24 days
Illumination 32.7 %, 35.3 %

Frank McCabe :)

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#2 Jef De Wit

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Posted 17 September 2009 - 09:50 AM

Long live the fog! Beautiful sketch.

#3 Tom Machtemes

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Posted 17 September 2009 - 10:02 AM


Nice sketch.



#4 Jeremy Perez

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Posted 17 September 2009 - 10:22 AM

Frank, it's great to see one of your graphite Lunar sketches. This is a fantastic drawing.

#5 kraterkid


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Posted 17 September 2009 - 11:43 AM

Gorgeous graphite rendering of Mare Humorum Frank! :bow: :jump: :bow:

The variation in the surface albedo or tonal values of the mare are very beautifully captured as are the dorsae or wrinkle ridges that arc across the lava flooded basin. Gassendi is modeled with such deftness, having a 3D quality to it. Looks like the libration really matched nicely, I can tell you carefully planned ahead for your second sketching session.

One of the wonderful lessons to take from this awesome sketch is that when you can't finish a sketch in a particular session, use your VMA or similar software to locate a phase/libration that would closely match your unfinished sketch. Sometimes that may only be a month as in your case Frank, and sometimes you may have to wait several months, but the results can be very rewarding as you have beautifully demonstrated in this exquisite graphite sketch my friend. :waytogo:

#6 frank5817



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Posted 17 September 2009 - 12:05 PM

Jef, Tom, Jeremy and Rich,

Thank you all for the nice words about my sketch.:thanx: The moon on the two dates of the sketch was much alike but not identical. I have another one from early spring I may never finish. It is good to know how much time you have in advance so you don't bite off more than you can sketch.
The fog did help with the intermediate tones but a polarizing filter would have worked with no fog.

Frank :)

#7 Tommy5



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Posted 17 September 2009 - 08:13 PM

Very nice lunar sketch one of your best, thanks for sharing.

#8 perfessor


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Posted 17 September 2009 - 08:19 PM

Very nice Frank. Gassendi is one of my favorites, and you have placed it so well in its environment.

#9 frank5817



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Posted 17 September 2009 - 09:13 PM

T5 and Tom,

Thank you both for your comment about my sketch. I was happy to be able to finish it.

Frank :)

#10 CarlosEH


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Posted 17 September 2009 - 10:12 PM


An outstanding observation of the Mae Humorum basin. The crater walls and shadows are well rendered. The Mare Humorum ridges (lava flows) look very nice as well. Thank you for sharing it with us all.


#11 frank5817



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Posted 18 September 2009 - 04:27 PM


Thank you, it was great fun to sketch this region of the moon. With the waning riding high this time of year, I just had to get out in the wee hours to sketch.

Frank :)

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