2026 Blue Moon phenomenon: will the moon actually turn blue?

A rare Blue Moon phenomenon will grace the night sky on Sunday, 31 May 2026, at 3:45 PM WIB.

Despite its name, does the moon actually turn blue?

The term ‘Blue Moon’ refers to the second full moon occurring within a single calendar month.

Broadly, there are two definitions of a Blue Moon: first, the second full moon in a calendar month; second, the third full moon in a season that contains four full moons.

This means that over a calendar year, the moon orbits slightly more than 12 times.

It is important to note that some months each year have 30 or 31 days.

Given the moon orbits slightly more than 12 times annually, some years will have 13 full moons. This ‘additional’ full moon typically occurs in one of the months, near the month’s end.

This phenomenon will be visible in the night sky at the end of May 2026.

Not only will it be a Blue Moon, but the full moon on Sunday, 31 May 2026, will also coincidentally align with a ‘Micro Moon’ phenomenon, where the moon appears smaller than usual.

The Micro Moon occurs when the moon is near apogee, the point farthest from Earth in its orbit. As a result, the moon appears slightly smaller and more distant than a typical full moon.