What is a “Dark Moon”?

17 July 2014

The Short Answer (TSA)

            “Dark Moon” is another term for “New Moon.”  The “New Moon” is one of the regular phases of the Moon.  The "New Moon" phase is considered to be the end of the old cycle of phases as well as the beginning of the new cycle of phases.

The Dark Moon 

(Also the "New Moon")

            During phase called “New Moon,” the Moon is said to disappear from the night sky.  Well, the Moon, itself, doesn't disappear.   But, during the “New Moon,” none of the Sun’s light is reflected by the Moon's face.  So, the “New Moon” is also the “Dark Moon.” 

            At the “Dark (New) Moon,” all light vanishes from the face of the Moon for a period of one and a half to three and half days.  The "Dark Moon" (and New Moon) begins when the last sliver of reflected sunlight disappears from the outer edge of the face of the Moon.  And, the "Dark Moon" ends when the first sliver of reflected sunlight reappears on the outer edge of the face of the Moon.  With this first bit of reflected light, “Dark Moon” phase ends and the “Crescent Moon” phase begins.

Moon's Phases (Northern Hemisphere)

            Until the 20th Century, the Dark and New Moon were not always considered to be the same thing.  During the 19th Century, seafaring records called the last day, or days, of the “Old Crescent Moon” -- just before the last light disappears from the Moon’s face – the Dark Moon.  And, the first day, or days, of the “New Crescent Moon” – just after the first light reappears on the Moon’s face – was called the New Moon.

            To make things just a bit more confusing, there’s not only a “Dark Moon,” but something called “The Dark of the Moon.”  “The Dark of the Moon” is a period of 3 days before the “New (or Dark) Moon.”  “The Dark of the Moon” was long considered to be an unfavorable time to plant crops or to begin new projects.  “The Dark of the Moon” was included with the phases of the Moon in old farmers’ almanacs.