Rare Blue Moonromoon Visible Worldwide

Skywatchers around the world observed a rare celestial event on the night of May 30-31, 2026, as a full moon known as a "Blue Micromoon" illuminated the sky. This event marked the second full moon within the month of May, a phenomenon that occurs approximately every two to three years.

The term "Blue Moon" refers specifically to the second full moon in a single calendar month, not to its color. The lunar cycle lasts about 29.5 days, and because most calendar months are longer, a second full moon can occasionally occur before the month ends. The first full moon of May took place on May 1 or 2, depending on location, making the moon on May 31 the qualifying Blue Moon.

Adding to its rarity, this Blue Moon was also a micromoon. This means the full moon occurred near apogee, the point in the moon's elliptical orbit when it is farthest from Earth. At this distance, roughly 252,000 to 406,000 miles away, the moon appears slightly smaller and dimmer than an average full moon. Astronomers note the apparent size difference compared to a supermoon can be up to 14 percent, though this variation is subtle and often difficult for casual observers to detect with the naked eye.