May 2026 Blue Moon Times: Dr Greg Brown Sets 31 May at 9.45am BST
May 2026 blue moon times point to 31 May, when the full moon reaches 9.45am BST as a blue micromoon. Dr Greg Brown of the Royal Observatory Greenwich said the moon will be full long after it has set in the UK.
Brown said a blue moon can mean a second full moon in one calendar month. He added that a micromoon is a full moon close to the moon's furthest point from Earth, making this combination rare enough to happen about once every couple of decades.
Dr Greg Brown On Blue Moon
Brown drew a line between the monthly and seasonal meanings of blue moon. “This is where you get a second full moon in one single calendar month,” he said of the monthly version. “But occasionally you’ll get two, and the second one is referred to as a blue moon”
He also described the seasonal version: “Within those roughly three months you expect to get three full moons, but occasionally you’ll get four” and “And for some reason, it’s the third one which is referred to as the blue moon.” The event on 31 May uses the monthly definition.
31 May 2026 Viewing Time
The full moon time is 9.45am BST in the UK, 4.45am Eastern Time in the US and 6.45pm AEST in Australia. Brown said that for the UK, the full moon time comes “long after the moon has set,” so the best view will be on Saturday or Sunday night.
He said it will be “indistinguishable from being full the entirety of the night beforehand and basically the night after as well.” In the northern hemisphere, the moon will sit relatively low in the sky throughout the night, while in the southern hemisphere it will be very high.
Moonrise In 2053 And 2066
Brown said a micromoon appears about 14% smaller than a supermoon and about 6% smaller than a typical full moon. He added that the next occurrence for the UK appears to be in 2066 using the same definition, while some parts of the world, including the US, will have one in 2053.
The moon can also look blue for another reason entirely, when dust in the atmosphere from significant forest fires or volcanic eruptions creates a bluish tinge. That is a different phenomenon from the blue moon named in Brown's explanation, and the May event keeps the focus on the timing rather than color in the sky.
