Craters Kepler and Encke At nearly 11 days into the current lunation sunrise has just finished for the rim of crater Kepler. Even during this early morning view, some of the brightest rays of this crater were seen radiating eastward from the ramparts on that side. Kepler is a 31 kilometer diameter complex crater with a low central peak and a flat debris covered floor from inner wall slumping. As I saw it during the time of this sketch, the floor was in complete darkness and had the perception of great depth. Crater Kepler lies between the Oceanus Procellarum and the Mare Insularum both of which consist of dark surface lavas.
The Jesuit astronomer Giovanni Battista Riccioli named Crater Kepler 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 for his three laws of planetary motion.
I was hoping to include Rima Milichius in this sketch but the seeing was so poor I never saw a hint of it even at its widest part that would have been located in the lower left corner of the sketch. The other crater captured in this sketch is 1 kilometer smaller in diameter and 3 times older than Kepler. This is crater Encke named after 19th century German astronomer Johann Franz Encke. The rubble-covered floor of this crater was well illuminated because of its greater distance from the terminator and much shallower depth.
Sketching and Equipment:
For this sketch, I used black Strathmore 400 Artagain paper 9” x 12”, white and black Conte’ pastel pencils and blending stumps. Telesccope: 13.1 inch f/6 Dobsonian and 9 mm eyepiece (222x) riding on an equatorial platform Date: 2-14-2011, 00:30-02:00 UT Temperature: 4° C (40° F) Partly cloudy, very windy Seeing: Very poor – Antoniadi IV-V Colongitude 39.8 ° Lunation 10.9 days Illumination 96.7 %