Don't miss the rare black moon rising August 22—it will be years until the next one. Here's why it'll help you see the Milky Way

Fast Company

5 hours ago

It's safe to assume you've heard the term once in a blue moon, which refers to the rare occurrence when there is a second full moon in a calendar month. But you might not have heard the term 'black moon.'
However, on Saturday, August 23 at precisely 2:06 a.m. EDT, a black moon is taking place. Although it sounds like something out of a dystopian novel, it's not that ominous. Let's take a deeper look at what this all means.
What is a black moon?
Much like great artists like Picasso, the moon goes through phases. The moon's version is cyclical, lasting around 29.5 days. A full moon occurs when Earth is between the sun and moon, and the side of the moon facing Earth is lit up by the sun.
A new moon is the exact opposite of a full moon. It occurs when the orb is between Earth and the sun, however, the side facing Earth is shadowed and dark, making the phenomenon invisible to the stargazer.
Similar to a blue moon, if two new moons occur in the same month, the second is considered a black moon.
Are there variations of a black moon?
There are actually two types of black moons.
The second type of black moon is based on seasons. It is the moniker given to a third new moon in a season of four new moons which is what is happening this weekend. For those in the North Hemisphere summer began on June 21 so new moons took place on June 25 and July 24 making August 23 the third in the line up. The fourth will take place on September 21 which is just a day before the equinox signaling the beginning of fall.
How often does a black moon happen?
Seasonal black moons only happen about once every 33 months according to Time and Date.
What does this have to do with the Milky Way?
To some degree our home galaxy, the Milky Way, is always visible in the night sky. During the summer months, the center of this massive grouping of stars, planets, and dark matter rises higher making it more visible to the naked eye. A black moon sky is the perfect time to attempt to see the Milky Way because the night is even darker than normal. So although you cannot see a black moon per se, it might just benefit your Milky Way viewing.