From 5:16 to 6:41 a.m. Bostonians and others on the East Coast looking up into the northwestern sky saw the moon completely bathed in a dark red hue in a total lunar eclipse. Tuesday morning’s was the final one until 2025.

Sometimes referred to as a blood moon, a lunar eclipse occurs when the Earth is perfectly positioned between the moon and the Sun, casting the Earth’s shadow over the moon and giving it a reddish appearance.

Those waking up early to cast their ballots in the state election got a glimpse of the blood moon before heading into the polls. Historically, lunar eclipses have been seen as bad omens. In ancient Inca civilizations, lunar eclipses were seen as a jaguar attacking and eating the moon. In Hindu folklore, lunar eclipses were explained as the demon Rahu drinking the elixir of immortality. Meanwhile some denominations of Christianity associate the lunar eclipse with God’s wrath.

This is the first time in U.S. history that a total lunar eclipse fell on Election Day—and thanks to NASA keeping an eclipse calendar spanning from 1999 B.C. to 3000, we know that it won’t happen again for another 372 years.

The previous total lunar eclipse occurred in May and was notable for being a “Super Flower Blood Moon,” meaning the eclipse happened when the full moon was at its closest point to Earth.

Lunar eclipses themselves are not particularly rare, with four occurring in the next two years—though only three of the four will be visible in Boston. However, total lunar eclipses—where the entirety of the moon is covered by the Earth’s shadow—are much rarer; the next will occur on March 14, 2025.

Unlike solar eclipses, lunar eclipses are safe to look at with the naked eye because, despite its bright appearance, viewers are still looking at the moon. With solar eclipses however, despite its dark appearance, you are looking directly at the sun with only the moon covering it.

The next lunar eclipse that will be visible in Boston will occur on Oct. 28, 2023. It will be a partial lunar eclipse.