The moon will turn a shade of red before passing into the Earth’s shadow for a total lunar eclipse Tuesday.
The “blood moon” is a normal part of a total lunar eclipse. Lunar eclipses occur when a full moon passes through the shadow of the Earth. In a total lunar eclipse, the moon slips into the darkest part of Earth’s shadow, called the umbra, which causes it to appear red, according to NASA.
In that position, the moon only receives sunlight that has passed through the Earth’s atmosphere. As the space agency puts it, “It’s as if all the world’s sunrises and sunsets are projected” onto the moon.
Next week’s eclipse will take place in the early hours of election day in the United States. NASA shared a chart last month showing the timing of different stages of the eclipse in the Eastern and Pacific time zones, with the moon slipping completely into Earth’s shadow at 5:17 a.m. ET and 2:17 a.m. PT.
The phenomenon will be visible across North and Central America, Asia, Australia and parts of South America. After next week, a total lunar eclipse will not occur again for about three years.