In May 2026, the sky will prepare a rare surprise: two full moons in one month. According to the Moscow Planetarium, the first will be visible on May 1st, and the second on May 31st. It is this second full moon that has received the unusual name – the "blue" Moon.
Despite the name, the color of the satellite will not change, as it is not related to astronomy, but to language: the expression "once in a blue moon" in English means an event that happens extremely rarely. In meaning, it is close to the Russian "posle dozhdichka v chetverg" (literally "after a little rain on Thursday," meaning "never" or "very rarely").
The phenomenon itself is quite simple to explain. The interval between full moons is about 29.5 days – slightly less than a calendar month. Because of this, from time to time, a situation arises where two full moons "fit" into one month.
Such occurrences are infrequent, which is why the second full moon has been given a separate name. It will be observable on the night of May 31st – given clear weather, the Moon will appear just as bright and full as usual, but the very fact of its "reappearance" in the same month makes the event special.
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