The rarity of events and celebrations such as milestone birthdays and cosmic happenings makes them special. The phrase “once in a blue moon” exists because it is not an everyday occurrence. This year, May has not one but two full moons lighting up the night sky, the second of which is going down tonight, in the early morning hours of Sunday, May 31. Illumination reaches its peak at 4:45 a.m. ET. But this is also considered a micromoon. Here’s everything you need to know before you stargaze. What is a blue moon? This has nothing to do with color. There are two ways to define a blue moon. The first is when a second full moon occurs in the same calendar month. This happens about once every 30 months . Tonight is the night for May 2026, as the first full moon took place on May 1. The second definition deals in quarters. A typical astronomical season contains three full moons. Every two to three years , a fourth sneaks in, causing the third full moon to be considered a blue moon.…