First Quarter lunar features
All photos by Damian Peach
Vallis Alpes is a cleft that bisects the Montes Alpes range. The valley is narrow at both ends and wider along its middle. Look carefully for small details here. Can you see that the southern face is straighter than the northern side, which is slightly bowed and uneven? The more rugged edges of the valley lie at the narrow west-southwest end that cuts through the mountain range.
Cassini Crater lies at the eastern end of Mare Imbrium. The flooded floor of the crater shows many impacts. The largest crater that sits entirely within the rim is Cassini A, just northeast of center. A hilly ridge runs from it to the southeast. Near the southwest rim is the smaller crater Cassini B.
Aristillus is a prominent crater with a bright ray system. Use a low-power eyepiece and you’ll see it extending for more than 370 miles (600 km). Then switch to high power and look carefully for the faint remains of a ghost crater off Aristillus’ top left edge. It’s almost buried by ancient lava flows.
Autolycus is a small impact crater just to the south of the more prominent Aristillus Crater. It has a faint impact-ray system extending outward, and some of the material crosses the floor of nearby Archimedes Crater.
Manilius Crater formed through an impact on the northeast edge of Mare Vaporum. It has a well-defined rim with a sloping inner surface that runs down to the ring-shaped mound along the base. The small interior crater is more reflective than the surroundings, and it appears bright when the Sun is overhead.
Hipparchus is the degraded remnant of a lunar crater near the Moon’s center. This ancient feature has been modified by subsequent impacts. Horrocks Crater lies entirely within its northeast rim. Halley Crater is attached to the south rim, and Hind Crater lies to the southeast. To the north-northeast is the bowl-shaped Pickering Crater, and lava-flooded Saunder Crater lies off the northeast rim.
Albategnius Crater is so large that lunar scientists often refer to it as a walled plain or a ring mountain. Look closely at the most prominent overlapping craters: Klein, which sits to the lower left in this image, and Albategnius B, just inside the northern rim at the top. Note that Albategnius’ outer wall has a rough hexagonal shape.
Stöfler is a large impact crater located in the Moon’s southern highlands. Look for Faraday Crater, which overlays its western edge. The rim of Stöfler is worn, but its outline remains intact except at Faraday. In a reverse of Manilius Crater, Stöfler’s floor has a low reflectivity, making the crater easy to identify.
Heraclitus is a complex crater in the Moon’s rugged southern highlands. Licetus Crater forms the northern end of the formation. Just to the east is Cuvier Crater, and due south is Lilius Crater. The entire formation is heavily worn, with features smoothed down by a long history of impacts.
