Basin – Page 2 – Astronomy Sketch of the Day

Three Rings Around a Target

The Southwestern Limb of Moon with Montes Rook and Cordillera
Sketch and Details by Peter Mayhew

Object Name: Southwestern Limb of Moon with Montes Rook and Cordillera.

Object Type: Lunar mountains

Location:

Date: 3rd October 2009

Medium: Graphite pencil on white paper.

Instrument: Skywatcher Skyliner 150mm f8 Dobsonian, 10mm e.p. with x2 Barlow.

Seeing: Very turbulent with intermittent stillness.

The Montes Rook and Cordillera with labelled features
Sketch and Details by Peter Mayhew

The moon was 14 days old and this part of the south west limb was the only region under contrast. Craters were only visible when close to the terminator, or if rayed or darkened with basalt flows. The mountain peaks stood out perfectly in moments of stillness. The three concentric mountain rings around the (not-visible) Mare Orientale were clearly defined. I include a labelled version.

The Sea of Moisture Through the Fog

Mare Humorum, the “Sea of Moisture”
Sketch and Details by Frank McCabe

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 Marie 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.

Sketching:
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

A Humorum Aside

Lunar crater Gassendi on the shores of Mare Humorum
Sketch and Details by Richard Handy

One hundred and fourteen kilometers in diameter, filled with rilles and a rich variety of terrain, Nectarian era Gassendi sits on the northwestern shores of Mare Humorum in the South West Quadrant of the Moon. Gassendi is a great example of a FFC (Floor Fractured Crater). Why is it fractured? Well, the real lowdown on the rilles is that they are created by magma that finds its way to the surface through weaknesses and fissures in the breccia beneath Gassendi. As the magma fills these volumes, it pushes up on the material on the crater floor causing these characteristic fractures in the surface and in the process providing a vent for lavas. The really amazing thing was the number of rilles on the floor that were bifurcated, some seemly splitting at obtuse angles while others paralleled the rim. I could sense that there was a level of detail hidden by the seeing, a larger population of smaller rilles awaiting that moment of perfect clarity to reveal themselves. However with Antoniadi III as my average, it wasn’t going to be tonight. On the northwestern wall of Gassendi resting on its northwestern margin, much as Gassendi is to Humorum, is 33 km Copernican era, Gassendi A. Above and to the northwest is the 26 km flat floored Gassendi B. I wonder how much is floor fill is from his bigger and (younger?) brother to the south, the result of slow and steady mass wasting or a carpeting of material from a larger event. The whole area to the north and west of Gassendi seemed to be filled with these arcuate grooves. Towards the southern sunken rim of Gassendi, the northwest part of a Basin rim seemed elevated above the Mare as it rose to meet a collapsed section of Gassendi’s rim in the middle of the western outer wall. I could tell the area to the west of this arc had a different texture to the terrain, as if they were only partially submerged in the mare lavas. There were arcuate rilles here as well, paralleling the Basin. I hoped you all enjoyed this, I know I had a rille wonderful time sketching this one and sharing it with you.

Here are the sketch details:

Subject: Gassendi and environs Atlas: Rukl 52
Date: 9-3-06 Start time 4:20 UT Ending time: 5:56UT
Seeing: Antoniadi III with moments of II every 3-5 min, Weather: clear to partly cloudy
Lunation: 11.38 days Colongitude 46 deg Phase: 49.9 deg
Illumination: 82.2 % Lib. in Lat. : +6 deg 28 min Lib. in Long.: – 6 deg 53 min
Telescope: 12″ Meade SCT F10
Binoviewer: W.O. Bino-P with 1.6X Nosepiece
Eyepieces: W.O. 20mm WA Plossls
Magnification: 244X
Sketch medium: White and black Conte’ on Black textured Conte’ paper
Sketch size: 18″ x 24″

The Sea of Crisis at Full Moon

Mare Crisium
Sketch and Details by Aleksander Cieśla, text by Rich Handy

This superbly drawn sketch of Mare Crisium by Aleksander Cieśla shows that the 638 Km
Nectarian aged Sea, even during Full Moon, still displays details such as its platform
massifs, isolated mesa like formations, and its circular scarps that identify it
as a Multi Ring Basin.

Sketch Details

The Fullmoon.

Object: Moon – Mare Crisium
Scope: Schmidt-Cassegrain 5” + Speers-Waler 7,4mm
Filter: Moon&SkyGlow
Place: Poland, Wroclaw – near city center
Weather: Good. Seeing 7/10. Light Pollution.
Date: 12 January 2009
Technique: White pastel crayons on black paper
Tooling: Contrast and gamma levels only

Basin Bailly

Lunar Basin Bailly
Sketch and Details by Frank McCabe

The terminator was approaching the southwestern limb of the moon as the basin Bailly, nicely visible due to favorable libration, came under full illumination. Bailly is large for a crater but small for a ringed basin at 300 kilometers in diameter. In the grazing sunlight the irregular basin floor with numerous craters was evident but no sign of the inner crater ring was visible as can be seen in overhead spacecraft images. The far side inner wall was beautifully illuminated in direct sunlight while features beyond were in total darkness. The depth of this basin is about 6 kilometer below the rim. The two large bright rimmed craters at the south end of Bailly’s floor are first older Bailly B at 65 km. and then younger Bailly A at 38 km. Also notable in this view is a portion of a bright ray of ejecta traceable back to Tycho (not in the drawing) and crossing crater Kircher (75 km.) before reaching the south end of Bailly. The 3 large craters below the Tycho ray are in descending size: Bettinus (73km.), Segner (70km.), and Zucchius (66 km.) which is the youngest of this group of craters.

This was the first evening the moon has been visible from my location since this lunation began. Although a little bit on the chilly side for sketching, it was a pleasure to get out and draw the moon again.

Sketching:

For this sketch I used: black Strathmore 400 Artagain paper 9”x 7”, white and black Conte’ pastel pencils and a blending stump. After scanning, Brightness was decreased (-2) using the scanner.

Telescope: 10 inch f/ 5.7 Dobsonian and 9 mm eyepiece 161x
Date: 12-11-2008, 5:15 – 7:00 UT
Temperature: – 3°C (26° F)
clear, calm
Seeing: Antoniadi III
Colongitude 73.1 °
Lunation 13.58 days
Illumination: 97 %
Libration: in Lat. -6° 3’, in Long. -3° 45’

Frank McCabe