The First Blue Moon in Two Years Will Light Up the Sky This Weekend—Here’s When to See It

Early on Sunday, May 31, the moon will reach its full phase for the second time in a single calendar month—a phenomenon known as a Blue Moon. The full Blue Moon will peak on Sunday, May 31, at 4:45 a.m. ET, according to the Farmer's Almanac. However, the best time to catch its striking orange appearance will be during moonrise near dusk on Saturday, May 30. No special equipment is needed to see it.

Despite its name, a full Blue Moon has nothing to do with the color. The phrase "once in a Blue Moon" refers to something very rare because Blue Moons occur only about every two to three years, according to Space.com. Since full moons happen every 29.5 days, two full moons can occasionally fall within the same month.

This year, the full Flower Moon rose on May 1. Now, 29.5 days later, the full monthly Blue Moon is set to rise once again.

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According to Forbes, a Blue Moon often appears orange as it rises because its light passes through a thick layer of Earth's atmosphere near the horizon. During a process called Rayleigh scattering, shorter blue wavelengths scatter, causing the moon to appear orange or reddish.

For the best view, find an open, southeastern horizon at the time of moonrise, which you can determine based on your location here. As the moon rises, you'll be able to spot the large glowing moon with the naked eye. For an even better view, bring along a pair of binoculars.