A Rare Black Moon Is Going to Coincide With Tomorrow's Solar Eclipse

There's an extremely rare celestial event happening Saturday night, and you won't want to miss it.

Ever hear of a Black Moon? Though it's not an official astronomy term, a Black Moon is when there's a second new moon in a calendar month — you can consider it the companion to a Blue Moon, which is a second full moon in a calendar month.

Ever hear of a Black Moon? Though it's not an official astronomy term, a Black Moon is when there's a second new moon in a calendar month — you can consider it the companion to a Blue Moon, which is a second full moon in a calendar month.

A rare occurrence that only happens roughly every 29 months, two alternative definitions of Black Moons, 

According to Timeanddate.com, include when there's no new moon in the month of February and when there are four new moons in a season — the Black Moon is the third new moon in that sequence.

Since a new moon occurs when the sun illuminates the far side of the moon rather than the Earth-facing side, you can't actually see a new moon from Earth — meaning astronomy enthusiasts won't technically be able to see Saturday's Black Moon either.

Saturday's Black Moon happens to coincide with a partial solar eclipse — an exceptionally rare combination. 

Solar eclipses occur when the moon travels between Earth and the sun, casting its shadow onto the surface of the Earth — a total solar eclipse means that the entirety of the sun will be blocked by the moon, whereas a partial one means just a slice of it will be covered.