The black moon is a special even that happens about every two and a half years. The black moon is the name given to the second new moon in a single month.
The black moon gets its name from the fact that when it happens, the earth facing side of the moon is completely covered by earth's shadow. This causes the moon to be almost completely invisible.
When?
The black moon will happen for the Western Hemisphere on September 30th at 8:11pm Eastern time. The Eastern hemisphere will get to see the event on the 1st of October.
Go see this interesting event because it won't be back for another 32 months :)
Sources:
upload.wikimedia.org/wikipedia/commons/d/dd/New_Moon.jpg
www.telegraph.co.uk/news/2016/09/28/black-moon-set-to-rise-this-week-in-rare-lunar-event---but-what/