A lunar eclipse formed a blood moon on late Sunday night (May 15, 2022) and the early hours of Monday morning. During a full lunar eclipse, the moon passes through the darkest part of the Earth's shadow. When the moon is within the umbra it gets a reddish hue because blue and green light get more easily scattered by dust particles in the atmosphere and orange and red colors remain more visible, according to NASA. Lunar eclipses are sometimes called blood moons because of this phenomenon.