Blue Moon May 2026 Brings Rare Micromoon on May 31
May’s blue moon may 2026 peaks at 8:45 a.m. UTC on May 31, and this full moon carries a rare double label: it is both a blue moon and a micromoon. The moon will not actually look blue, but it will appear slightly smaller and dimmer than usual.
Blue Moon May 2026
Seth McGowan, president of the Adirondack Sky Center in Tupper Lake, New York, said, “A ‘blue moon’ doesn’t refer to color. It’s a calendrical term.” In May’s case, the term refers to a monthly blue moon, meaning the second full moon in a calendar month.
McGowan also said, “This definition is older and comes from traditional almanac usage.” Blue moons have two accepted definitions, monthly and seasonal, and the seasonal version is the third full moon in an astronomical season that has four full moons instead of the usual three.
Adirondack Sky Center Timing
The full moon reaches peak illumination at 8:45 a.m. UTC on May 31. The best time to observe the micromoon is after moonrise on May 30 or in the early morning hours of May 31, depending on location. Observers should look toward the eastern horizon if there are no clouds.
No telescope is necessary to look at the moon. Binoculars can help reveal craters and the dark volcanic plains known as maria.
Micromoon and Apogee
A micromoon occurs when a full moon coincides with apogee, the moon’s farthest point from Earth. A full moon at perigee is called a supermoon, and a micromoon can appear roughly 10 to 15 percent smaller in apparent diameter than a supermoon.
McGowan said, “Most casual observers wouldn’t notice the difference without a side-by-side comparison, but careful observers or photographers can detect it.” Blue moons occur every two to three years because the lunar cycle lasts roughly 29.5 days, and the moon’s elliptical orbit changes its distance from Earth during each orbit. In 1883, after the eruption of Krakatoa, observers around the world reported seeing blue-tinged moons.
