"In a total lunar eclipse, the entire moon falls within the darkest part of Earth’s shadow, called the umbra. When the moon is within the umbra, it appears red-orange. Lunar eclipses are sometimes called 'blood moons' because of this phenomenon," Caela Barry wrote for NASA.

A total lunar eclipse is a relatively rare astronomical event because the moon usually passes above or below Earth’s shadow in the sky due to the tilt of its orbit. But once or twice a year the heavens literally align and the moon moves directly into that region of space.