Astronomers use the phrase “black moon” to refer to four distinct celestial events. The Farmer’s Almanac refers to a black moon as a third new moon in a season that has four of them. A black moon could also mean the absence of a full moon in a calendar month or absence of a new moon in a calendar month.
A black moon is the second occurrence of a new moon in a single calendar month. It happens approximately every 32 months and tonight, it will rise above the Western Hemisphere — but it won’t be visible from earth.
Black moon dates vary from year to year. In 2015, the black moon occurred in February and in 2014, it occurred in March. In 2017, the black moon will rise on October 21.
The Eastern Hemisphere will also experience the same moon, but not until October 1. This means their black moon won’t actually occur until the second new moon of October, on the 30.
The biggest bummer? Unlike the blood moon, there are no apocalyptic prophecies associated with the black moon, so if you wanted to use the end of the world as an excuse for excessive partying tonight you’re out of luck.
Much like astronomers, witches also aren’t on the same page about what exactly the black moon means. Some believe the astrological event can make spells more powerful than normal while others think the moon makes any rituals or spells ineffective. If you’re not interested in casting spells, many Wiccans say the black moon can be a good time to start over and rid yourself of bad habits (a second new moon means twice as many chances this month). Who needs a juice detox when you have moon energy?
Photos via NASA, Getty Images / Handout