Blue Moon phenomenon observed across multiple regions in Indonesia

The Blue Moon phenomenon was visible across several Indonesian regions, including Jakarta, Banda Aceh in Aceh, and Pulau Balikukup in Berau, East Kalimantan, on Sunday, May 31, 2026.

A Blue Moon refers to the second full moon occurring within a single calendar month. According to the National Research and Innovation Agency (BRIN), the first full moon of May 2026 occurred on May 1, with the second on May 31.

Astronomically rare, the Blue Moon phenomenon occurs approximately once every one to three years. Despite its name, the moon does not appear blue; the term denotes the occurrence of two full moons in the same month.

The next Blue Moon is expected on December 31, 2028, making it a highly anticipated event for skywatchers and the general public.