Black moon years. When February is without full moon, then the preceding January or December and the following March or April have two full moons. As with the case of two new moons in a month, whether a black moon by this definition occurs depends on the time zone. Calculated in UTC, instances of a month without full moon between 1990 and 2040 are: Another use of the term is for the absence of the new moon in a calendar month. This can occur only in February; it happens about every 19 years. When February is without new moon, then the preceding
Geology of the Moon Geology of the Moon The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar science") is quite different from that of Earth. The Moon lacks a significant atmosphere, which eliminates erosion due to weather; it does not have any form of plate tectonics, it has a lower gravity, and because of its small size, it cooled more rapidly. The complex geomorphology of the lunar surface has been formed by a combination of processes, especially impact cratering and volcanism. The Moon is a differentiated body, with a crust, mantle, and core. Geological studies