If you look up in the sky early Sunday morning, you’ll be able to catch the peak of a rare blue micromoon glowing in the sky.
As the term “once in a blue moon” suggests, these moons aren’t the most common phenomenon. They occur around once every two to three years, according to the Royal Museums Greenwich. These moons aren’t actually blue in color – the name often refers to a second full moon occurring in one month, per the Old Farmer’s Almanac.
That’s what this calendrical blue micromoon is, the second full moon of May. A Flower Moon kicked off the month back on May 1. Sometimes, “blue moon” refers to the third of four full moons in an astrological season. In that case, it is considered a seasonal blue moon rather than a calendrical full moon, the Smithsonian magazine explained. It also said that “micromoon” is an unofficial term.
Now that we’ve got the “blue” part of this moon sorted out, let’s move on to the “micro” part. According to information provided by NASA, micromoons occur when the Moon’s fully illuminated phase close to the time when the moon is furthest from Earth in its orbit of our planet (known as apogee).
Since the moon will be further away than usual, it will appear smaller than it usually does to us here on Earth. Sunday’s blue micromoon will be quite subtle, it’s the farthest and dimmest moon of the entire year. Micromoons are the opposite of supermoons that occur when the moon is closest to Earth.
“The moon orbits Earth in an elliptical path, with one side closer and the other farther,” said the Old Farmer’s Almanac. “While this affects its size and brightness, the difference is too subtle to notice with the naked eye. What often makes the moon appear larger is the ‘moon illusion’ – an optical effect that occurs when it’s near the horizon. Since this micromoon will be high in the sky, it likely won’t appear as large or imposing as a full moon closer to the horizon.”
A concurrence of a blue moon and micromoon is relatively rare, the Smithsonian magazine noted. NASA’s information said that a blue micromoon will appear in the sky for another 27 years. Another micromoon is expected next month and the last blue moon in August 2024 was a supermoon.
To catch a glimpse of this shy and distant moon, the Old Farmer’s Almanac suggests finding a location with unobstructed views of the horizon at around 4:45 a.m. EDT on May 31. The almanac’s Moonrise and Moonset Calculator can help sky gazers determine when the moon will be visible in their area.
