How to Best See This Weekend’s Rare Blue Micromoon

A blue moon is not actually blue in color; the name simply refers to the rarity of the phenomenon. Before first being applied to the second full moon in a month—mistakenly—in a 1946 issue of Sky and Telescope magazine, the term used to refer to the third of four full moons in a single season. 

A micromoon, meanwhile, is a full or new moon at the farthest distance in the moon’s orbit from Earth, a point called apogee. 

Saturday night’s blue micromoon is a combination of the two phenomena: it will be the second full moon of May, and it will also reach apogee, making it appear roughly 10% dimmer and 6% smaller than an average full moon, according to Gianluca Masi of the Virtual Telescope Project, who spoke to The Associated Press. 

The moon will be this year’s smallest-looking moon, at approximately 252,360 miles (406,134 km) away from Earth. The average distance of the moon from the Earth is around 238,900 miles (384,472 km).