It has been cold in Chicagoland and although it was sunny most of the day, high cirrus clouds moved in after sunset to block out all stars fainter than 3rd magnitude. Ice crystals at high altitude generated a colorless halo around the Moon. Not the best conditions for sketching but the first chance in 4 weeks for me. My target for this sketch was the pair of craters at the southern edge of Oceanus Procellarum. Crater Billy (46 km.) with its dark smooth lava covered floor and crater Hansteen (45 km.) with its hilly, irregular floor and terraced walls present contrasting looking craters of similar size and age. Between these craters is a large arrowhead shaped volcanic extrusion feature called Mons Hansteen. This object always looks very bright at or near full Moon.
Black Canson paper, white and black Conte’ pastel pencils, white Pearl eraser, blending stumps
Telescope 13.1” f/6 Dobsonian telescope on an equatorial drive platform at 222x with 9mm eyepiece
Date: 12-04-2014, 02:00 – 03:00 UT
Temperature: -7°C (20° F) mostly cloudy, calm
Seeing: Antoniadi IV (poor)
Colongitude: 54.2 °
Lunation: 11.4 days
Illumination: 92.5 %
Across the Carpathian Mountains resting on the eastern Ocean of Storms is the
landmark crater of the Sea of Islands, mighty Copernicus. Copernicus is a 95
kilometer diameter complex crater that begins to show itself in all its majesty
two days past first quarter. During the time of “Snow-Ball Earth” 800 million
years ago the event that created Copernicus suddenly occurred. What remains is a
3.8 kilometer deep hummock covered flat floored, centrally peaked, terrace walled
spectacular sentinel. Especially during high sun the bright ray system of this
crater can be seen extending from the base of the glassy glacis in all directions.
The descent from the rampart to the mare floor below is about one kilometer. Three
of five peaks were clearly visible in morning sunlight. In 1999 the Clementine
near infrared camera detected magnesium iron silicates in the peaks indicating
rebound of this deep rock through the surface crust following the impact event.
To view this impressive crater all you need is a good pair of binoculars and an
opportunity between two days past first quarter and one day past last quarter.
Weather permitting, you can see it tonight.
For this sketch I used: black Strathmore 400 Artagain paper, 9”x 12”, white and
black Conte’pastel pencils and a blending stump.
Telescope: 13.1 inch f/5.9 Dobsonian and 9mm eyepiece 218x
Date: 11-03-2014, 00:45 – 02:10 UT
Temperature: 0°C (32°F)
Seeing: Antoniadi III
Co longitude: 23.2°
Lunation: 8.9 days
Illumination: 69.3 %