fault or graben – Page 2 – Astronomy Sketch of the Day

When a Wall is a Window

The Straight Wall
Sketch and Details by Jacques Thibault

Find enclosed one of my many drawings of the Straight Wall.
I used my D & G refractor, 127 mm achromatic, f/12, mounted on
Losmandy GM8.
18 mm and 12 mm Radian eyepieces and T-V 2X Barlow. (range : 84X
-260X, mostly 130X)
Conditions : Seing 4/5, from my backyard in Sainte-Foy, Quebec.

My working method :

1-Prior to observing, I make an outline drawing with the help of the
Hatfield Atlas. I use the outlined maps. This takes care of the
proportions and locations of the craters.
That way, I am able to concentrate on the lighting.
2-At the eyepiece, I note the shades of gray with Ansel Adam’s zone
system (0-10).
3-Back in the studio, I make a new outline on drawing cardstock (very
lightly, with a 2H graphite pencil).
4-I then use dry pastel to impart the general shade of the drawing. I
really push on the stomp to dye the paper.
5-I give a light coat of fixative to protect the pastel and to make
sure the ink will catch on the pastel surface.
6-Then I use India ink for the large black zone and different
Letraset markers to finish the drawing.
I also use an electric eraser to clear the white and to create texture.
During the drawing process I will browse in my many books on the Moon
and a wide collection of pictures taken from the Internet and other
sources.

I am not trying to make scientific observations. I just like being
alone under the stars, late in the night or early before sunrise :
it’s like walking alone by the ocean. I chose to draw because it’s by
far the best way to relive the experience. I dont make astro
photographs because I dont want to transform what is for me a
spiritual and relaxing activity into a technical marathon. I share my
drawings with my family and friends.

The very best seing to you all!

Jacques Thibault
Quebec.

I saw so many beautiful drawings on your fabulous site that I felt
that I had to send something as a token of my gratitude. Merci beaucoup.

Jacques

Pardon My Hyperbole

Rima and Rupes Cauchy
By Rich Handy

Scanning the area to the west of the famous hyperbola shaped rille and rupes pair, I was pleasantly surprised to see each extending further in that direction (Rupes and Rima Cauchy become faint rilles) and passing by some of the most interesting pyroclastic deposits, lunar domes and cinder cones I’ve ever seen on the lunar surface. Each extend further in the eastern direction as well. Unfortunately I’d need two large sheets to sketch this area in the kind of detail it deserves, so I settled for this somewhat smaller vista. Check out Chuck Wood’s “The Modern Moon” page 88 and 89 for an excellent overview of this exciting area and Rukl Atlas Plates 36 and 37 for a detailed view of this amazing area. Rima Cauchy is just to the north of Cauchy, a 14 km, bowl shaped Copernican era crater that sits amidst the eastern Sea of Tranquility and pretty close to Sinus Concordiae, the mare area that tapers off to the north. To the south is Rupes Cauchy, its wall brightly lit in the the last rays of the late lunar afternoon. Immediately to the south of the Rupes were the two domes, Cauchy Tau to the west (right) and Cauchy Omega to the east. I noted the central peak on Omega with no problem, a testament to the kind of seeing I was blessed with last night. Though I couldn’t say with absolute certainty, there seemed to be two “Arago-like” domes below 12 km Eratosthenian aged Zahringer near the smaller 11 km Taruntius F.

Next time you are observing this area, take some time to visit this rare fault and rille and it’s terribly interesting environment. It may sound like hyperbola, but I’m not exaggerating, this place is lunie dreamland!

Here are the sketch details:

Subject: Rima and Rupes Cauchy and environs Rukl: 36,37
Date: 9-10/11-06 Started: 6:40 UT End: 8:24 UT
Seeing: Antoniadi I-II Weather: Clear most of session then fog late.
Telescope: 12″ Meade SCT F10
Binoviewer: W.O. Bino-P with 1.6X Nosepiece.
Eyepieces: W.O. WA 20mm Plossls
Magnification: 244X
Lunation: 18.48 days Phase: 311.1 deg Illumination: 82.9%
Colongitude: 133.7 deg Lib in Lat.: -3 deg 53 min Lib in Long.: +5 deg 12 min
Sketch medium: White and black Conte’ Crayons on black textured Strathmore paper.
Sketch size: 18″ x 24″

Shadowplay on the Floor of Ancient Thebit

The Straight Wall, Birt, and Thebit on the floor of ‘Ancient Thebit’
By Richard Handy

What struck me immediately was the scimitar shaped shadow of the Straight Wall. I had observed the Wall on many past ocassions and I guess I had never seen it so close to the terminator. The long shadow cast by the fault (the “absolute best example of a lunar fault” according to Chuck Wood) amply displayed the fact that Ancient Thebit must have subsided on it’s western half into the Nubium basin. Ancient Thebit is the large circular partial rim flooded with mare lavas which dominates the center of the sketch. It is not to be confused by the snowman shaped 57 km Upper Imbrium crater Thebit, which lies within it along with Birt
and the Straight Wall. I’m not totally sure about my interpretation, but I believe that Rima Birt is demarcated by the shadow line just immediately above Birt, the small double crater on the left of the Straight Wall. The crater at the lower right is Purbach with its scattering of low peaks and small craters on an otherwise lava flooded floor.

Here are the sketch details:

Subject: Rupes Recta, Birt, Thebit on the floor of “Ancient Thebit”.
Date: 8-31-06 Start time- 3:40 UT Ending time- 4:27 UT
Lunation: 8.31 days Phase 88.1 deg Colongitude: 8.6 deg
Libration in Latitude: +6 deg 48 min Libration in Longitude: -6 deg 43 min
Telescope: 12″ Meade SCT f/10
Binoviewer: W.O. Bino-P with 1.6X Nosepiece
Eyepieces: 20mm W.O. Plossls
Magnification: 244X
Sketch medium: White and black Conte’ Crayon on black Strathmore Artagain paper.
Sketch size: 9″ x 12″

Janssen and Fabricius in the Lunar Southeast

Janssen at 195 kilometers in diameter is a large ancient (4 billion year old)
walled plain crater in the southeastern highlands and is not far from the lunar
limb. Relentless moonquakes and solar system debris impacts have given this crater
its old look. The floor of Janssen is covered by numerous smaller craters. Without
trying too hard I could see 20 crater including those down to a few kilometers in
diameter. The center of the crater appears to bulge higher than the worn rim. Much
of this could be debris from the large much younger impact crater Fabricius (79
km.). Fabricius is an Eratosthenian period impact crater. It clearly shows steep
sloping walls and exhibits a central mountain range that is about 11 km. long and
also a long central ridge that is more than twice that length. Geologists tell us
that much of the debris across the floor of Janssen is Nectaris impact ejecta;
fluidized where the floor is smooth and irregular boulder-like where the floor
appears tortured. But perhaps the most interesting feature here is 140 kilometer long Rimae
Janssen. This rille looking like a graben, where it cuts through the high central
region south of Fabricius. It then narrows suddenly before reaching the rim in the
relatively smooth region of the floor. Pits that are visible via high resolution
images in these narrow regions imply volcanism. There is at least one dome on the
floor of Janssen but I was not successful in spotting it in the current
illumination. Craters Janssen and Fabricius presented fascinating features to
examine during this observation.

Sketching:
For this sketch I used: black Strathmore 400 Artagain paper, 7”x11”, white and
black Conte’ pastel pencils and a blending stump. Brightness was slightly decreased after
scanning.

Telescope: 10 inch f/ 5.7 Dobsonian and 6mm eyepiece 241x
Date: 9-29-2007 6:15-7:15 UT
Temperature: 16°C (60°F)
Clear, calm
Seeing: Antoniadi III
Co longitude: 122.1°
Lunation: 17.73 days
Illumination: 91.4 %

Frank McCabe

Even craters have their faults

Here is my impression of the Lunar Crater Taruntius. It was sketched with a #2HB
0.5mm mechanical pencil on Strathmore Wind power Sketching Paper. Other pertinent
details are on the sketch itself. What caught my eye with this particular lunar
feature was the ring of hills wrapping around the central peak.

Jason Aldridge
Florida, USA

The Ever Popular Rupes Recta

In the morning hours before sun-up the early waning crescent moon was superimposed
on the firmament just west of the Pleiades. I was somewhat transfixed by this
scene but I was set up to sketch “straight wall” on the floor of the lunar Sea of
Clouds. From the eastern edge of Mare Nubium you can see the Triplet craters
Thebit (57 km), A and L. Next moving westward is the Imbrian escarpment Rupes
Recta , not a true wall in the usual sense but on one side standing more than 300
meters high at some points and 114 km in length. The scarp face would be visible
from crater Birt (17 km) to the west, the youngest of the larger craters sketched
here. Touching the rim of Birt to the east is Birt A. Continuing westward we see
Rima Birt a 51 km rille from the Imbriam epoch. At the end of the rille to the
south, is tiny 3 km crater Birt F seen in this sketch. Finally sitting on a
wrinkle in the floor of the mare is crater Nicollet (15 km) a Eratosthenian epoch
impact scar.


Sketching:
For this sketch I used: white copy paper, graphite pencil and pen and ink
Contrast adjusted with Imageenhance software
Telesccope: 18 inch f/ 5 Dobsonian working at 222X (9mm ocular)
Date: 8-16-2006 9:30-10:35 UT
Temperature: 17°C ( 62°F)
Clear, calm
Seeing: Antoniadi III
Colongitude 178 °
Lunation 22.3 days
Illumination 45.9%

Frank McCabe