Seth McGowan Explains Full Moon May 2026 Blue Micromoon
The full moon may 2026 reaches peak illumination at 8:45 a.m. UTC on May 31, and it carries two labels at once: blue moon and micromoon. Seth McGowan, president of the Adirondack Sky Center in Tupper Lake, New York, said the blue moon term is calendrical, not a color description.
McGowan said, "A ‘blue moon’ doesn’t refer to color. It’s a calendrical term," and May’s event fits the most widely known definition, a second full moon in a calendar month. He also noted that blue moons happen every two to three years because the lunar cycle lasts roughly 29.5 days and does not line up with calendar months.
Adirondack Sky Center
The other half of the double label comes from the moon’s orbit. A micromoon happens when a full moon reaches apogee, the point where it is farthest from Earth. That is the opposite of a supermoon, which occurs at perigee. In this case, the moon may appear slightly smaller and dimmer than a typical full moon.
McGowan said, "Most casual observers wouldn’t notice the difference without a side-by-side comparison, but careful observers or photographers can detect it," and the effect can be about 10 to 15 percent smaller in apparent diameter than a supermoon. Binoculars can help reveal craters and the dark volcanic plains known as maria.
May 30 and 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. The peak itself comes later that morning at 8:45 a.m. UTC, when the full moon reaches its fullest illumination. McGowan said, "This definition is older and comes from traditional almanac usage," referring to the seasonal blue moon definition, which uses the third full moon in an astronomical season that has four full moons instead of the usual three.
For readers planning to look, the practical window is the evening moonrise on May 30 and the early hours of May 31, when the moon is visible and the size difference can be studied. The event brings together the monthly blue moon definition and the apogee-based micromoon in one lunar cycle.
