Residents across the United States were able to witness a full lunar eclipse and blood moon Friday morning. A lunar eclipse occurs when the sun, Earth and moon align so that the moon passes into Earth’s shadow.

In a total lunar eclipse, the entire moon falls within the darkest part of Earth’s shadow, called the umbra. Long wavelengths of sunlight are refracted through Earth’s atmosphere before reaching the moon, which reflects them in reddish hues that may resemble the color of blood. When the moon is within the umbra, it appears red-orange.

Lunar eclipses are sometimes called blood moons because of the phenomenon. The lunar eclipse reached its maximum phase at 2:59 a.m. Friday, with totality — the period in which the moon is completely engulfed in the Earth’s shadow — lasting for about 65 minutes.