The Moon on July 30, 2009

This image shows an area of the Moon that includes the Apollo 17 landing site (in the upper right-hand corner of this image). Mouse over this image and an annotated version of the image appears that has features shown in the image labeled, including the Apollo 17 landing site. Apollo 17 was the last manned mission to the Moon in the Apollo program. On December 11, 1972, it touched down near Littrow crater. Using a lunar rover vehicle, Eugene Cernan and Harrison Schmidt explored further and remained outside their LEM longer than any previous mission. They also visited a dark halo crater on the south-eastern border of Mare Serenitatis named Shorty, and solved the mystery of the enigmatic dark halo craters found in some places on the Moon. Such dark halo craters appear to be the result of impact explosions that excavate dark mare material from beneath a thin layer of lighter regolith. The Apollo missions brought back a total of 381.7 kg of lunar rocks. Three successful Russian probes went to the Moon after Apollo 17.

The two craters named Messier and Messier A are located on the Moon's eastern side about 2 degrees south of the Moon's equater. You can find them in the lower center of this image. Messier is an oblong crater that is 5.6 miles by 6.8 miles, indicating that it must have resulted from a low angle impact. Messier A next to it is similarly oblong in the same direction, measuring 8.1 miles by 6.8 miles. One of the most interesting features of these two craters is the two linear rays that extend from Messier A for more than 60 miles in a westward direction. These two rays extending such a long distance in only one direction obviously must have been the result of a very low angle impact. Messier and Messier A were named after the famous French comet hunter Charles Messier who published the Messier Catalog.

The small crater Censorinus is only 3.8 km in diameter, but it grabs attention because of the patch of bright highly reflective ejecta surrounding it. Censorinus is probably one of the youngest craters on the Moon that can be resolved with a backyard telescope. The interior of this crater is bowl-shaped.

Torricelli crater is located near the top center of this image. Torricelli crater is noteworthy because of its keyhole-shaped or pear-shaped appearance. This resulted when an adjacent crater took out its west wall. Torricelli crater is 14.3 miles wide. Torricelli is located within the faint outline of a low-contrast circular formation known as Torricelli R, which is visible in this image. Torricelli R appears to be an ancient crater that was filled with a lava flow that almost completely covered the crater. The prominent crater just below it in this image is named Torricelli A, which has a diameter of 6.8 miles. Torricelli A lies just outside the outer rim of Torricelli R.

Mare Crisium is visible to the naked eye as a dark patch near the Moon's northeast limb. Mare Cricium is distinctive because it is completely detached from the main system of lunar maria. The Crisium basin formed about 3.9 billion years ago, and a subsequent episode of lava flooding covered it with a smooth dark floor of solidified basaltic lava. The basaltic covering extends to about 1 km deep in the center of Mare Crisium. Promontorium Agarum is an impressive cape projecting into Mare Crisium. The highest peaks in this formation tower several thousand feet high. The largest crater in Mare Crisium is Picard, which is 23 km in diameter. Lick is the remnant of an old flooded crater. Yerkes is a broken partial ring that represents the remains of another ancient crater almost completely obscured by a subsequent lava flow. Under the right lighting conditions when the sun angle is low, the raised ridge of Yerkes combines with Greaves crater and the surviving wall of Lick along the shoreline of Mare Crisium to form an effect nicknamed "the flying eagle."

Proclus is a 28 km diameter crater about 70 km west of the shore of Mare Crisium. This crater has a very bright system of rays that are remarkably asymmetric. Faint rays cross onto Mare Crisium, but the most prominent rays extend northwest of the crater. The triangular-shaped dark region situated east of Mare Tranquillitatis is called Sinus Concordiae (Bay of Harmony). Along its northern border is an area called Palus Somni (Marsh of Sleep), which includes the remaining region to the northeast of Proclus that is not covered by rays.

The crater Langrenus is situated on the eastern shore of Mare Fecunditatis (at the bottom edge of this image). It has a splendid appearance when the lunar terminator is nearby. However, in this image it is illuminated with a high sun angle. The crater's bright interior shows well in this image. The crater has a double central mountain formation that is 1000 meters high.

Theophilus is the large crater at the top left edge of this image. The crater rim rises up 1.2 km above the crater's surroundings. The interior of the crater, however, is 3.2 km below the crater's surroundings. The complex inner slopes of Theophilus can be seen in this image. A magnificent central mountain cluster displays peaks that are 2 km above the floor of the crater. The Mare Nectaris lavas encroached right up to the eastern flanks of the rim of Theophilus crater. The crater Madler sits at the junction between Mare Nactaris and Mare Tranquillitatis.

This CCD image of the Moon was taken with a Takahashi FCT-150 refractor with a 4x PowerMate at f28 using an SBIG ST-8XE CCD. This image of the Moon was taken when it was nine days old, and the waxing Moon was past first quarter. The side of the Moon facing us was 72% illuminated, and the Moon was 28 degrees above the horizon. In this image, north is to the left.

July 30, 2009
Image by Sid Leach
Scottsdale, Arizona

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