On Monday, observers of the skies will once again have the opportunity to experience a rare "black moon." There was already a black moon on December 1, which makes this celestial phenomenon extremely rare.

A black moon also refers to the new moon phase itself when the moon is positioned between Earth and the sun, making it nearly invisible from our view. The black moon is a new moon in Capricorn, an Earth sign associated with ambition, professional goals, societal structures and authority, according to Thomas.

A rare black moon will appear in the sky on December 30, making it a perfect night to go stargazing. Here's what you need to know.