rays – Page 4 – Astronomy Sketch of the Day

A bright note in his Music of the the Spheres

Crater Kepler and its Rays

At nearly 12 days into the current lunation sunlight is bathing young crater
Kepler and its extensive ray system. Kepler falls into the category of a smallish
complex crater (31 km in diameter and 2.75 km deep) with a low peak rising from an
otherwise small flat central floor. Most of the floor is covered with slumped wall
debris. A small part of the inner wall appeared terraced. Crater Kepler lies
between the Oceanus Procellarum and the Mare Insularum both of which are made of
dark lavas. Very prominent rays extend from the rampart and ejecta blanket well
beyond the crater rim for more than 300 km. Some of the rays, especially in the
east, overlap rays of other craters such as Copernicus.

Crater Kepler was named by the Jesuit astronomer Giovanni Battista Riccioli about
28 years after the death of Johannes Kepler. He also named Crater Tycho after
Tycho Brahe, the man with the accurate data measurements that helped make Kepler
famous.

West northwest of Kepler the large old crater close to the terminator is Marius.
Using a higher magnification ocular than that used in this drawing, I could see
several domes to the north of the crater in very good grazing light. Kepler is a
favorite crater target of mine as the moon approaches full phase.

Sketching:
For this sketch I used: black Strathmore 400 Artagain paper 9”x12”, white and
black Conte’ pastel pencils and a blending stump.
Telesccope: 10 inch f/ 5.7 Dobsonian and 9 mm eyepiece 161X
Date: 4-29-2007 2:45-3:45 UT
Temperature: 18° C (65° F)
Clear, calm
Seeing: Antoniadi III
Colongitude 51.8 °
Lunation 11.6 days
Illumination 90.5 %

Frank McCabe

Brightest Heliocentrist

When I visit the Moon with my telescope, unless I’m working with friends on a collaborative project, I like to see what takes my fancy when I reach the terminator. Invariably something catches your eye and just won’t let it go, that is what I go for, he who shouts the loudest. On the evening of Saturday April 28th it turned out to be Aristarchus magically illuminated along the terminator.

I used my Antares 105mm F14.3 refractor, viewing through a Denk binoviewer
yeilding 163x.

Using a black sketching pad and a mix of watercolour pencils, pastel pencils and
conte sticks after 15 minutes this was the result.

Dale Holt

On the edge of a fertile sea

Langrenus at the Edge of the Sea of Fertility

With the Harvest moon just past and the shadow of the setting sun approaching the eastern shore of the Sea of Fertility, crater Langrenus stands out in all its glory. Langrenus is an Eratosthenian Period crater, between one and three billion years old. This crater is about 133 km. in diameter with a rim 2.6 km. above the bright, mostly flat floor. Mountain peaks near the center stand 1 km. high. Rays from the crater can be seen projecting in a westward direction across the Sea of Fertility. Much older (four billion plus years) and slightly larger than Langrenus to the south along the terminator is the crater basin Vendelinus. The walls of this crater were dealt crushing blows delivered by the impacts that created craters Lohse, Lame and Holden which are drawn clockwise from north to south. Many additional smaller crater impacts on Vendelinus attest to the age of this old battered basin.

More than 400 km. to the northwest, grazing angle impaction created the craters Messier and Messier A. These craters exhibit a long pair of rays extending westward across the remainder of the mare. Note the perpendicular (north-south) rays centered on Messier. Laboratory experiments have demonstrated this pattern of so called “butterfly rays” can be duplicated with shallow angle high speed impacts.

Frank McCabe

Sketching:
For this sketch I used: white copy paper 6”x 8”, and a 2HB graphite pencil
at the eyepiece with the addition of marker ink to darken shadows indoors.

Telesccope: 10 inch f/ 5.7 Dobsonian and 9mm eyepiece
Date: 10-9-2006 5:00-5:45 UT
Temperature: 10°C (50°F)
Clear
Seeing: Pickering 5
Co longitude: 114 °
Sunset longitude: 66.1° E.
Lunation: 16.8 days
Illumination: 94%