According to the folks at Living With The Moon, a Black Moon is a rather rare occasion (about every 2.5 years) and refers to the 2nd New Moon in one calendar month.
So that's really all there is on the surface, but esoterically, wow! A Black Moon is seen as a real turning point, either globally or in your private life. The key word here is "change." And like the Winds of Change Bob Dylan sang about in the early 60's, a Black Moon means change or new directions when it hits.
Of course, the Christian predict the return of Christ every chance they get, which is silly, since they've been doing this since the beginning of their faith, which really has to be a downer, and regarding the Black Moon it is no different, for example, for the Black Moon on Friday, September 30th, 2016, the Christian blog "Express" wrote:
Warning BLACK MOON tonight: Astrological event to herald 'End of Days' and second coming
That writer went on to state:
TONIGHT'S Black Moon could bring with it worldwide destruction and the second coming of Jesus Christ, Christians and conspiracy theorists have claimed.
Of course, again Jesus doesn't show, but that's okay for most of us.
According to NASA the Black Moon is... wait, they don't define it because it is not a big deal; furthermore, the term "Black Moon" only goes back to 2016, because, well, it is only a month with two new moons in it. Not an astronomical event.
Historically, the theme of events from the recent "Black Moons" or second new moon in a calendar month between 2010 and 2020 are:
*July 7th, 2011 - Moscow bans the book L. Ron Hubbard Scientology book.
*January 30th, 2014 - French Socialist Party defeated in major upset.
*October 30th, 2016 - FBI announces it will be reviewing Liberal President Hillary Clinton's email, a month before the presidential election; which gives Donald Trump the presidential election a month later.
*August 30th, 2019 - DOJ report finding the FBI violated policy investigating Donald Trump in 2016. Pro-democracy protesters arrested in Hong Kong.
*August 22nd, 2025 - To Be Determined, but whatever it is, "Dark Moons" seems to be favor President Donald Trump.
Finally, for the Pagan in us all, here is the Pagan definition according to
Spiritually, the Black Moon is a powerful time for shadow work, release, and deep transformation as it combines and amplifies the energy of the New Moon and the Dark Moon. Whether you see it as the ultimate lunar reset or a chance to plant long-term intentions, the Black Moon’s energy invites you to go inward, shed what no longer serves you, and trust in the unseen process of growth.