Dorsae – Astronomy Sketch of the Day

Craters Diophantus and Delisle

On the western side of Mare Imbrium are craters Diophantus (19 km.) and Delisle (25 km.) with mons Delisle in between and closer to the crater of the same name. A dorsum or ridge here is perhaps a buried crater rim and creates a sharp edge curving demarcation on the terminator side of the Moon at the time of sketching. Some of the massifs in this region such as mons La Hire (1.5 km. high), mons Vinogradov (1.4 km.) and mons Delisle( 0.8km. high) are described by some geologists as likely left over remnants from the rings of the Imbrium impact. Additional craters seen at this observation included Euler (2.8 km.), Artsimovich (9 km.), Gruithuisen (17 km.) and Heis (15 km.)and numerous smaller unnamed.

Sketching:

For this sketch I used: black Strathmore 400 Artagain paper, 9”x 12”, white and black Conte’pastel pencils, a soft charcoal pencil, brush and a blending stump.

Telescope: 13.1 inch f/6 Dobsonian and 9mm eyepiece 221x
Date: 01-31-2015, 03:10 – 04:25 UT
Temperature: -7°C (20°F)
clear, breezy
Seeing: Antoniadi III
Co longitude: 38.7°
Lunation: 10.33 days
Illumination: 84.9 %
Phase: 45.8°

Frank McCabe

Crater Posidonius at Sunset

Lunar crater Posidonius and environs at sunset - August 7, 2012 — Lunar crater Posidonius and environs at sunset – August 7, 2012

Crater Posidonius at Sunset

On this night I watched the sunset terminator creep slowly toward ring-plain crater Posidonius; in addition I sketched the crater and other features on the floor of Mare Serenitatis. Posidonius (96 km.) is an old upper Imbrian era impact remnant. Its age is underlined by the way shadows penetrate the rim at numerous points betraying impact damage there. The highest part of the rim is on the terminator side of this crater. Sunlight was still reaching Posidonius A and other high points on ridges including one on the inner ring. Beyond this crater to the west and south the great serpentine ridge could be seen in best light. This ridge is made up of dorsa Smirnov and dorsa Lister.
 Sketching:

For this sketch I used: black Strathmore 400 Artagain paper 9″x 12″, white and black Conte’ pastel pencils and a blending stump. After scanning, Brightness was decreased just slightly using my scanner.

Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241x
 Date: 08-07-2012, 06:30 – 07:40 UT
 Temperature: 29°C (85° F) clear, calm
 Seeing: Antoniadi III
 Colongitude 147.9 °
 Lunation 19 days
 Illumination: 73.4 %

  Frank McCabe

Gassendi at Terminator

Lunar crater Gassendi - October 4, 2014 — Lunar crater Gassendi – October 4, 2014

Object Name: Gassendi
Object Type: Lunar Crater
Location: Dunboyne Ireland
Date: 4th October 2014
Media: Graphite pencil H2, H3 & B6 with standard white stock and technical drawing equipment.

This is actually sketched as observed through the eyepiece with a 15mm on a 9.25 SCT rather than from the phone screen. The seeing was fair but a weather front was fast approaching and just managed to observe long enough to capture this detail. At the same time I took some snapshots through the eyepiece with my smartphone for a smartphone astronomy site – so got to do both before the clouds rolled in. Adding the phone to the sketch allows me to add a technical drawing into the mix which I not (only) enjoy but also allows me to capture the evenings activities and optical equipment used during the session.

Many Thanks

Kevin

Crater Gassendi and the northern part of Mare Humorum

Lunar crater Gassendi and the the northern part of Mare Humorum - September 5, 2014 — Lunar crater Gassendi and the the northern part of Mare Humorum – September 5, 2014

Here is a sketch of the Moon on the 5th of September from my backyard
in Adelaide, South Australia.

The moons phase was waxing at 83%, with only the very western edge
still in shadow. I observed with a C11 SCT. Seeing was quite
reasonable, so I took a 15mm eyepiece + 2x Barlow for a close look.

The shallow illumination on Mare Humorum made the creases on the mare
floor stand out. Crater Gassendi, toward the bottom, showed stark
shadows. Rimae Hippalus was visible, passing through the partially
submerged crater Hippalus at the top right. Because I used a diagonal
prism, the sketch is mirror imaged.

I used pastel chalks and black and white pastel pencils on black
paper.

-Ivan

Dorsa Euclides F and Euclides

Dorsa Euclides and the lunar crater Euclides - August 6, 2014 — Dorsa Euclides and the lunar crater Euclides – August 6, 2014

Dorsa Euclides F and Euclides

Object Type: Moon

Location: Tarragona – Spain

Usually it is not easy for me to draw the moon, and if I have to draw something as delicate as lunar wrinkle ridges (dorsa / Dorsum), things get complicated. But the time I spent enjoying Dorsa F Euclides, Euclides and the neighbors ghost craters worth it.

For more details of my observation you can visit my blog:

http://laorilladelcosmos.blogspot.com.es/2014/09/dorsa-euclides-f-euclides.html

Date and Time: 2014-08-06, 21h 50m UT

Telescope: SC Celestron 235mm (9.25″); CGEM mount.

Eyepiece: 7.5mm (313x)

White paper, HB2 graphite pencil, and scanned with Photoshop

Seeing: 4/5 (5 the best)

Transparency: Clear. Rural skies.

Thank you and best regards.

Oscar

Lambert & Mons La Hire

Made this sketch of crater Lambert, Mons La Hire and Dorsum Zirkel and surrounding areas this evening, using my 505mm mirror and Watec video camera on its least sensitive setting. The view on the monitor was delightful and one I shared with optical designer and engineer Mr Es Reid of Cambridge, all very civilized and enjoyable.

The sketch was made on black A5 220gm art paper using Conte hard pastels and acrylic paint for bright highlights and deep shadow.

I hope you like it.

Kind regards, Dale

Do you want to know more about my interest in astronomy? If so take a look at my Website: www.chippingdaleobservatory.com

Keep up to date with observations from Chippingdale Observatory by reading the Blog http://chippingdaleobservatory.com/blog/

Ancient Thebit and Rupes Recta

Ancient Thebit, Rupes Recta, Thebit, Birt, Promontorium Taenarium
Move mouse over image to view labels.

Object Name: Ancient Thebit, Rupes Recta, Thebit, Birt, Promontorium Taenarium
Object Type: Lunar crater, lunar graben, lunar dorsum.
Location: York, UK
Date: 3rd December 2011
Media: graphite pencil, white paper

The straight wall, or Rupes Recta, is the best example of a simple fault on the moon, and visible even with a small scope. It’s 300m high and 114km long. It lies radial to the Mare Imbrium impact basin, in line with a lot of nearby sculpture from that event, but that is probably just coincidental. It also lies in line with the edge of the Mare Nubium basin and cuts across the floor of an ancient crater lying across the edge of that basin, known as Ancient Thebit, whose eastern edge marks the edge of Mare Nubium and western edge is marked by wrinkle ridges in the mare. Rupes Recta marks where the edge of Mare Nubium would have been if Ancient Thebit had never formed. The sequence of events is therefore likely to have been:

1. Nubium impact occurs, forming Nubium basin (4.55-3.92 billion years ago).

2. Ancient Thebit impactor hits edge of Nubium Basin.

3. Nubium basin floods with lava forming Mare Nubium (approx 3.3 billion years ago according to crater counts), flooding Ancient Thebit.

4. Nubium basin slumps in the centre, forming Rupes Recta along its former edge.

I failed to see Rima Birt, a lava rille that travels from a dome on the northern border of ancient Thebit to crater Birt. However, seeing was not good. I did nonetheless make out the dome that marks its origin, which I had not seen before.

Herschel C and Dorsae

Date: 13/04/2011
Object: Herschel C crater
I prepared this picture: Photoshop CS2

Clear sky! 🙂

Viktor Cseh

Sunset Terminator Across Mare Crisium

Mare Crisium is that interesting isolated sea on the northeastern side of the visible lunar surface. Only about half of it was visible during this sketching session.
The Nectarian Period event that formed this feature occurred more than 3.8 billion years ago. The mare portion of the basin is about 500 kilometers across. In the grazing sunlight across the floor, wrinkled ridges were visible in the north to south direction. Also on the western floor craters Picard (24 km.), Peirce (19 km.) and Swift (11km.) stood out in the low light. I could clearly see the lighter colored bench lava that partly buried craters here such as Yerkes (37 km.). Tall flat top mountains (massifs) beyond the shore stand at 2-5 kilometers above the sea. Also beyond the sea to the West crater Proclus (28 km.) with its remarkable bright rays was reflecting some sunlight.

Sketching:

For this sketch I used: 400 series black Strathmore Artagain paper 9″x 12″, white and black Conte’
pastel pencils , and Conte’crayons, a blending stump, plastic eraser. Brightness was decreased -2 and contrast increased +1 using the scanner for this sketch
Telescope: 10 inch f/ 5.7 Dobsonian with 6mm (241x)
Date: 12-23-2010 10:00 – 11:30 UT
Temperature: -8°C (18°F)
Weather: clear, calm
Seeing: Antoniadi III
Co longitude: 120°
Lunation: 17.7 days
Illumination: 94.5%

Oak Forest, Illinois

Frank McCabe

Burning Candles at Both Ends

Clear skies and a prominent day-11 moon on the evening of 16th December had me out really enjoying sketching; it wasn’t too cold (to begin with), the skies were clear, the target was high and I had plenty of time…..all a rare occurrence.

I sketched one of the most architecturally pleasing parts of the moon; the Sinus Iridum, which is a large crater/small basin with a partially flooded rim.

Of the two promontories, the one on the right (Promontorium Heraclides) is also known as the moon maiden, because at certain times it resembles the profile of a lady, with her long hair falling away off her shoulders. Also visible are the wrinkle ridges which might be traces of the buried rim, and craters Bianchini, Maupertuis, La Condamine and Bouguer.

Awaking on 17th at 4am with busy thoughts, I decided that viewing Saturn would be better than attempting to get back to sleep. And so it was.

I was surprised by quite a lot. The rings had opened up quite a bit since I saw them last spring. Not being close to opposition, the planet was quite small and I couldn’t see much detail on the planet itself. Only one moon was obvious; Titan predictably. With effort, another moon could be viewed roughly forming a right-angled triangle between Titan and the planet; it’s the faint spot at middle-left of the picture. This turned out to be Iapetus, which was pleasing because I haven’t seen that very often. It was new for me to see a moon so out of plane with the planet and the rings as last year they were mostly in line. It was good to see such old friends again.

* Object Name – Sinus Iridium, Mare Imbrium; Saturn, Titan, Iapetus.
* Object Type – Lunar Crater, Mare; Planet, Moons.
* Location – York, UK
* Date 16th December 2010, 17th December 2010
* Media – Graphite pencil on white paper. Observing instrument: Skywatcher Skyliner 152mm f8 Dobsonian, 10mm e.p., x2 Barlow.