Blue Moon Visible Across Indonesia on 31 May 2026

A rare Blue Moon phenomenon will occur on Sunday, 31 May 2026 and will be visible across Indonesia if the skies are clear. This astronomical event is expected to peak at 15:45 WIB (Western Indonesian Time). ‘It can be viewed from Indonesia. The Blue Moon appears like a normal full moon,’ said Thomas Djamaluddin, a researcher at the Space Research Centre of the National Research and Innovation Agency (BRIN). He also confirmed that the full moon retains its pale yellow-white colour during the Blue Moon phase. Despite its name, the phenomenon does not cause the moon to appear blue. This rare occurrence has given rise to the phrase ‘once in a blue moon’, meaning something very uncommon. Generally, a Blue Moon has two definitions. The first is the second full moon in a single calendar month, as will occur on 31 May 2026. The second is the third full moon in a season that contains four full moons. Essentially, the moon takes approximately 29.5 days to orbit the Earth. Over a calendar year, this cycle results in slightly more than 12 full moons. Meanwhile, some calendar months have 30 to 31 days. The May 2026 Blue Moon coincides with a micromoon, a condition where the moon appears smaller than usual. A micromoon occurs when the moon is near apogee, its farthest point from Earth in its orbit. As a result, the moon appears slightly smaller and dimmer than a typical full moon. The Blue Moon and micromoon phenomena are expected to be visible across various regions of Indonesia, provided the skies are clear of clouds or rain.