A rare celestial event will take place on May 31, 2026, when the second full moon of the month — commonly known as a “Blue Moon” — will appear in the night sky.
The first full moon of May was seen on May 1, while the second is scheduled to rise on the final day of the month, making it a relatively uncommon astronomical occurrence.
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Despite its name, a Blue Moon does not actually appear blue in colour. The term is used when two full moons occur within a single calendar month, with the second one being referred to as a Blue Moon.
Astronomy experts note that because of this event, the year 2026 will feature 13 full moons instead of the usual 12.
The origin of the phrase “Blue Moon” is also considered unusual. According to reports, the term became widely popular after being mistakenly used by writer James Hugh Pruett in a magazine article during the 1940s.
There are generally two types of Blue Moons: seasonal and monthly. A seasonal Blue Moon refers to the third full moon in a season containing four full moons, while a monthly Blue Moon occurs when two full moons appear in the same month.
The last seasonal Blue Moon was observed on August 19, 2024, while the previous monthly Blue Moon appeared in August 2023.
Astronomers have also pointed out that both full moons of May 2026 will qualify as “Micro Moons.” This means the moon will appear slightly smaller and dimmer than a typical full moon.
The phenomenon occurs because the moon will be near its farthest point from Earth, known as apogee. During this period, the moon will be approximately 406,000 kilometres away from Earth.
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As a result, the May 31 full moon is expected to appear around seven per cent smaller and nearly 30 per cent less bright compared to an average full moon.
Skywatchers around the world are expected to observe the rare event, weather conditions permitting.