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
Full moon were less likely. All this is relevant to canine rather than human behavior. Historically, month names are names of moons (lunations, not necessarily full moons) in lunisolar calendars. Since the introduction of the solar Julian calendar in the Roman Empire, and later the Gregorian calendar worldwide, people no longer perceive month names as "moon" names. The traditional Old English month names were equated with the names of the Julian calendar from an early time (soon after Christianization, according to the testimony of Bede ca. AD 700). Some full moons have developed new names in modern times, e.g., the blue moon,