What is a Black Moon?
Much media hype surrounds Moon names, such as “Blood Moon” and “Blue Moon,” but have you ever heard of a “Black Moon”? This year, there’s a Black Moon on July 31. Here’s an explanation of this ominous-sounding name.
What is a Black Moon?
Like “Blood Moon” and “Blue Moon,” “Black Moon” is not an astronomical term. In fact, if you ask a sample of astronomers, both professional and amateur, very few will have even heard of it. It’s not even a particularly widely known folklore thing.
As for its definition, some people say it’s a “Black Moon” if:
- There is a new Moon twice in the same month. It’s similar to the Blue Moon, which has become a common term for the second full Moon in a month. This is the definition of Black Moon that’s used most often.
- There are NO new Moons in a month. This could only happen in February, and thus is kind of rare, meaning once every 5 to 10 years.
- The phrase might also simply refer to every new Moon, since we’re then seeing the Moon’s dark or black side.
- The phrase is also sometimes applied to mean the third new Moon when there are four in a season, which is actually one of the definitions of a “blue Moon” when the same thing happens to a full Moon.
There is no astronomical significance to a Black Moon. Nothing happens, except the usual new Moon absence of any Moon in the sky, plus the stronger so-called “spring” tides we get for a few days around every full Moon and new Moon.
When is the Next Black Moon?
If you’re willing to use any of the definitions above, you’ll get a Black Moon at least once a year, and sometimes twice. However, if we go by the standard “two new Moons in one month” definition, Black Moons become slightly more rare, occurring about every 32 months (two to three years).
In North America, the next Black Moon will occur on July 31, 2019, at 11:12 P.M. ET (August 1, 2019, at 3:12 UTC). This new Moon is the second of two July 2019 new Moons. (Or, in some time zones, it’s the first of two August 2019 new Moons.
Yes, it’s all about scheduling, folks!
What Will You See During a Black Moon?
Uh, not much. Like all new moons, it’ll cross the sky with the Sun during the day. Humans can’t see the new Moon in the Sun’s glare.
During the new Moon phase, the Moon is not illuminated by the Sun and seems to disappear from the night sky. A new Moon is practically invisible to the naked eye, so there’s nothing to see during a so-called Black Moon.
Remember, there are four quarters of the Moon—the Moon phases. There’s usually a new moon and a full Moon about once a month, because the Moon takes about a month to orbit Earth.
- You all know the “full Moon,” when the entire disk of the Moon is illuminated by the Sun (because they are on opposite sides of the sky).
- In contrast, the “new Moon” has its dark side facing us. It’s not reflecting any of the Sun’s light because the Moon is lined up between the Earth and Sun.
July 31 New Supermoon
This July, the new Moon is also a “supermoon” (i.e, the Moon is closest to Earth during its orbit during the new Moon phase.)
With a new supermoon, the tides will be extra large.
Specifically, the high tides are a little higher and low tides are a little lower than average. This is due to gravitational pulls that causes the oceans to bulge a bit more than usual, and called spring tides.
Stars Look Brighter
Although there’s not much to see when a Black Moon rises, the good news is that a moonless sky is excellent for stargazing (since the Moon’s light won’t drown out the stars). Check out our monthly star charts to know what to look for this month.
A day or two after the new Moon, you’ll see the slim crescent Moon in the west after sunset. By August 6, you’ll see the Moon in the night sky again.
What do you think about the Black Moon now? Should it carry any significance? Let us know in the comments! Happy stargazing!
About This Blog
Welcome to “This Week’s Amazing Sky,” the Almanac’s hub for everything stargazing and astronomy. Bob Berman, longtime and famous astronomer for The Old Farmer’s Almanac, will help bring alive the wonders of our universe. From the beautiful stars and planets to magical auroras and eclipses, he covers everything under the Sun (and Moon)! Bob, the world’s mostly widely read astronomer, also has a new weekly podcast, Astounding Universe!