Blue Micromoon Occurs This Weekend, Astronomer Says

The Story

A blue micromoon will appear this weekend, combining a monthly blue moon with a micromoon. Dr Greg Brown of the Royal Observatory Greenwich explained the event and how to view it.

Key Facts

• The blue micromoon occurs on May 31, 2026, with the full moon at 9.45am BST (4.45am ET, 6.45pm AEST).
• A monthly blue moon is defined as the second full moon in a single calendar month.
• A micromoon occurs when a full moon is near its furthest point from Earth, appearing about 14% smaller than a supermoon and 6% smaller than a typical full moon.
• A blue micromoon occurs approximately once every couple of decades, but intervals are irregular.
• For the UK, the next blue micromoon using the same definition is expected in 2066; some parts of the world, including the US, will have one in 2053.
• The moon will not appear blue; a bluish tinge can occur from dust in the atmosphere caused by forest fires or volcanic eruptions.
• In the UK, the moon will have set by the exact full moon time, but it will appear full on the nights of Saturday May 30 and Sunday May 31.
• In the northern hemisphere, the moon will be low in the sky; in the southern hemisphere, it will be high.
• The origin of the phrase “once in a blue moon” is uncertain; it may be linked to the rare blue tint from smoke or ash in the atmosphere.

Conflicting Reports

No conflicting reports identified in the source article.

Still Unclear

The article notes that time zone differences and the international date line can affect whether a full moon qualifies as a blue moon in different locations. The exact origin of the phrase “once in a blue moon” remains uncertain.

Misconceptions

The article clarifies that a micromoon will not appear as a tiny speck; it is only slightly smaller than a typical full moon. It also states that a blue micromoon is not actually blue in color unless atmospheric dust from fires or volcanic eruptions creates a bluish tint.

Key Figures

• Dr Greg Brown, astronomer at the Royal Observatory Greenwich

Sources: The Guardian