At the northeastern edge of the Moon disc we see prominent dark spots. The lava flooded floor of the crater Endymion, and the walled plain of Mare Humboldtianum. When the sunlight comes in at a lower angle, we see the mountainous edge that forms an almost closed circle around the Mare. Crossing the edge we find the crater Belkovich, which lays in the libration area.
BELKOVICH - Igor Vladimirovich Belkovich (Игорь Владимирович Белькович) (Born; October 15, 1904, OS: October 2, - Died: May 30, 1949) Russian Astronomer who worked at the Engelhardt Observatory of the University of Kazan. During this time he undertook a comprehensive measurement program, the program's result was the exact determination of the orbital parameters of the Moon and in particular their impact on the Libration.
Crater. (204Km /120Mi ø ) (61.5° N, 90.0° E) Situated in the zone of librations. Circular formation. Steep slopes supporting Hayn to the North-West Belkovitch A and B to the South and Belkovitch K to the North-East. High walls. Large flat floor with a rille. Central hill.
Crater. (129Km /76Mi ø ) (Dept: 4600m /13,900ft) (53.6°N 56.5°E) Circular formation. Very steep slopes supporting Endymion J to the West and Endymion A to the North-East. Very high walls especially to the South-East. Very large flat floor filled with somber lava. Small lines of crests.
MARE HUMBOLDTIANUM - Sea of Humboldt (Alexander von Humboldt) Born: 1769 Berlin, Germany - Died in 1859, Potsdam Germany. German Naturalist and explorer. Explorer of Venezuela, Colombia and Peru from 1799 to 1804. Exploration of Russia in 1829.