The Other Apennines
When we hear or read something about the Apennine Mountains, we naturally think of the spine of Italy running from just north of Genoa down roughly 500 miles to the toe of the Italian boot. It's a place of lush and spectacular scenery. The other, not so famous Apennine Mountain range also has spectacular scenery...but not so lush. It's in the Moon's northern hemisphere and runs almost 400 miles from just south of the crater Autolycus southwest to the crater Eratosthenes. While the lunar Apennines may not be as long as its Italian namesake, its peaks are higher with the tallest at close to 18,000 feet.
I took an image of the lunar Apennines on Monday night, June 13, 2016. Observing conditions weren't great. It was hot, steamy, hazy and partly cloudy to mostly clear with no wind. Sky transparency at my house was only 2nd magnitude but the seeing was a decent 7 out of a perfect 10. The Moon was just past first quarter, lighting up the Apennine peaks and rising on the crater Eratosthenes. I used my Celestron 11'' Schmidt-Cassegrain telescope (SCT) with the inexpensive Celestron Neximage 5 Solar System Camera at a wide field setting and my wife's laptop to take a video file of the Apennines. The video was processed in Registax where I stacked the 10 best frames of the 71 frame file. The finishing touches were made using Photoshop Elements. In the image below, north is upper left and lunar east is to the lower left.
The Apennines run left to right across the picture ending at the 36 mile diameter, 11,800 feet deep crater Eratosthenes. The rising Sun is just catching the crater's central peak and illuminating its terraced west wall. The darkness beyond marks the lunar terminator and the edge of night. On the left edge of the photo is the 51 mile diameter crater Archimedes. The floor of Archimedes and its central peaks were buried by the upwelling lavas that filled Mare Imbrium to the north of the Apennines. South of Archimedes (to that crater's right in this photo) is the Archimedes Mountains in a lighter, flat area toward the Apennines. This area is known as the Apennine Bench and is part of the floor of the original Imbrium impact basin which was high enough not to get flooded by the later Imbrium lavas. Toward the top of the frame in Mare Imbrium, the Sun is rising on the 21 mile diameter crater Timocharis, its floor still in complete darkness. At the left edge of the frame just below Archimedes is Palus Putredinis (or putrid marsh in English). It's about 111 miles wide and must have reminded Giovanni Riccioli, the 17th century astronomer who named it, of a garbage dump. Riccioli introduced the lunar nomenclature system we still use today. Riccioli also has a very large crater named after him near the western limb of the Moon.
If you look really closely toward the bottom of the Apennine Bench, there is a thin, dark line parallel to and above the Apennines slightly curving through some lower hills. This is the 80 mile long Bradley Rille. Deep in the mountains and overexposed in the bright sunlight is the 14 mile diameter crater Conon. It's 7,650 feet deep and much of its floor is still in the shadow cast by its east wall. The following image was taken with my Celestron NexStar 6" SCT on June 25, 2015. It is a stack of the best 20 out of 255 frames processed in Registax and Photoshop Elements. It is more of a close up of the section of the Apennines around Conon, but taken when the Sun was a bit lower in the lunar sky. The Bradley Rille can be seen in the hills to the right of Conon.
There's lots to see in this area and it's fun to explore the various features individually under higher power. Give it a try when the solar angle on this region is low enough for the elevated areas to cast shadows giving the features depth.
June 27, 2016