A rare Black Moon is coming September 30th

A rare Black Moon will emerge in the Western Hemisphere on September 30th -- but you won't be able to see it.

That's because the side of the moon lit by the sun faces away from Earth.

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A Black Moon is the second new moon of a month and a social phenomenon used to describe months with no full moons.

Ian O'Neill a Space Producer for Discover News says, "Social media has a huge part to play. These things go viral."

The term Black Moon isn't even recognized by NASA.

Click through the gallery to see previous Black Moons:

Another type of Black Moon is when no new moons occur in a month. These happen every five to ten years in February.

While the lunar event doesn't occur once in a blue moon. It does happen about every two years.

The next Black Moon is expected in July 2019.