2010 10 21, Kepler’s Rays

2010 10 21, 0545UT Kepler’s Rays
PCW Memorial Observatory, OH, USA, Erika Rix
Zhumell 16”, 8mm TV Plossl, 225x mag, no filter
Temp: 12°C, 42% humidity, S: Antoniadi III, T: 2/6
Sketch created scopeside with Rite in the Rain paper and charcoal.

Phase: 31.4°
Lunation: 12.46d
Illumination: 92.7%
Lib. Lat: -6°08’
Lib. Long: -1°16’
Az: 234°24’, Alt: 37°25’

Kepler’s Rays: Ray system stemming from Kepler, 38°W, 8.1°N
Copernician period (-1.1 billion yrs to present day)

Click thumbnail for labels

As I sit here at the kitchen table eating lemon drop cookies and drinking my coffee, I’m trying to concentrate on the reading material in front of me that discusses lunar rays on the Moon. First of all, it’s hard to concentrate while the two young dogs in the family are playing beside me; and secondly, I don’t have my reading glasses on, making concentration even harder. But I think what’s really getting to me is that the more I read, the more questions I have regarding rays.

Simply put, rays are streaks of ejecta that spray outward during the formation of impact craters. The larger pieces of ejecta can form smaller impact craters in the process. Rays may appear bright because of the abledo and/or thermal properties of the ejecta material differing from the surface material.

Lunar rays can assist (though not always) in comparing ages of features or other impact craters because of layering. Over time, space weather will erode or change the albedo of the materials, iron oxide may be more abundant in certain areas that may preserve the brightness of the rays making them appear newer, or other impact craters or lava flows may have destroyed them.

Sketching rays was not an easy task for me. I found it much more enjoyable to sketch all the craters in the area. My tips to anyone wishing to use white paper instead of black: draw in your craters first so that you have anchors for ray placements, concentrate solely on the dark areas, work in layers – light to dark, work in wedges around the origin crater, and finally…patience is the key. The craters are the easiest part of the sketch!

Resources:
Rukl plate: 30 Kepler
“A Photometric Investigation of the Lunar Crater Rays” by J. Van Diggelen
“Correlations Between Iron Abundances and Lunar Surface Features: Crater Kepler Area” by Lu Yangxiaoyi
“The Modern Moon” by C. Wood pg. 172 (mention of Kepler’s Rays), pg. 51 (Bright Rays)
Lunar Orbiter photos of Kepler
The Moon(LPOD) – Kepler

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~ by Erika Rix on November 18, 2010.

2 Responses to “2010 10 21, Kepler’s Rays”

  1. Another wonderful illumination Erika, both artistic and astronomical. I really like how you couple the Art of Astronomy with Astronomical Art. You’re compiling a terrific resource here and it’s a great example of how deeply some of us “Amateur Astronomers” are affected by the sheer beauty of what’s in the sky.

  2. Thank you! The enjoyment and fascination of astronomy is hard to beat when coupling the wonderment of the objects we view with trying to learn more about the objects in the process. One of the ways for a person to really study an object, as we know, is to try to sketch it as accurately as we can.

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