US

Rare 'black moon' rises over Western Hemisphere Friday night

FILE - In this Jan. 9, 2008, file photo, one day past New, an early Waxing Crescent Moon is seen just after sunset from Tyler, Texas. A rare "black moon" rises over the Western Hemisphere on Friday, Sept. 30, 2016. A black moon is the second new moon in a calendar month. (AP Photo/Dr. Scott M. Lieberman, File)

FILE - In this Jan. 9, 2008, file photo, one day past New, an early Waxing Crescent Moon is seen just after sunset from Tyler, Texas. A rare "black moon" rises over the Western Hemisphere on Friday, Sept. 30, 2016. A black moon is the second new moon in a calendar month. (AP Photo/Dr. Scott M. Lieberman, File)  (The Associated Press)

A rare "black moon" rises Friday night over the Western Hemisphere, but don't expect to see it.

NASA says a black moon is the second new moon in a calendar month. A new moon is the start of the lunar cycle and the phase where the moon is impossible to see because it's completely shrouded in darkness.

A black moon occurs about once every 32 months. Friday night's officially takes place at 8:11 p.m. on the East Coast.

The term "black moon" contrasts with "blue moon," which is the second full moon in a calendar month.