You don’t actually see it, but the rare black moon – the second new moon of the astronomical season – appears on August 23rd.
The term “Black Moon” is a more folk name, not an official label for astronomy, says Earthsky.org. This is a rare event, and occurs once every 33 months.
Simply put, the black moon is an extra new moon. (The new moon, one of the eight stages of the moon, is a moon that we cannot see.) A new moon occurs when the moon is between the Earth and the Sun. Its illuminated side is far from the earth, so it is invisible to us.
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Without the moonlight reflected during the new moon, it becomes easier to see stars and other celestial objects. That’s when amateur astronomers can take out telescopes and binoculars to study planets, stars and other deep objects.
Black Moon is unique as the 30 or 31-day calendar month is slightly different from the 29.5-day moon cycle. As the moon cycle doesn’t fit properly in them, the astronomical seasons also vary. Due to differences, the Black Moon can appear at irregular intervals.
Black Moon is mentioned as a blue moon, defined as the third full moon in the astronomical season, which includes four full moons. (Full Moon is a fully lit month.)
How is Black Moon defined?
Monthly Black Moon: The second new moon in the calendar month.
Seasonal Black Moon: The third new moon in the astronomical season of four new moons. There are four astronomical seasons, defined by the Earth’s position in its solar orbit.
- summer solstice
- winter solstice
- Autumnal
- Spring Equinox
Astronomical seasons usually have three new months. If there are four new moons in the season, the third is labeled as the black moon.
Source USA Today Network Report and Research. Reuters; NASA; space.com; iflscience.com; Earthsky.org; livescience.com; National Geographic
