FRANKFURT — A blue micromoon will occur on Sunday, May 31, 2026, when the second full moon of May coincides with the moon’s farthest point from Earth in its orbit. The event will reach peak illumination at approximately 4:46 A.M. Eastern Time.

The first full moon of May 2026 took place on May 1, setting the stage for the rare calendar occurrence. A blue moon is defined as the second full moon within a single calendar month and does not refer to the moon’s color. Blue moons happen roughly every two to three years.

On May 31, the moon will be approximately 252,360 miles (406,135 kilometers) from Earth. At this distance, the full moon qualifies as a micromoon, appearing slightly smaller and dimmer than an average full moon. A micromoon is the opposite of a supermoon, which occurs when the moon is closest to Earth and appears larger and brighter.

“The differences are subtle enough to likely go unnoticed by most observers,” Gianluca Masi of the Virtual Telescope Project said. During the night of the blue micromoon, the bright red star Antares will appear near the moon in the sky. The next blue micromoon after May 2026 will occur in December 2028.