A “Once in a Blue Moon” event occurs on May 31, when the second Full Moon of the month rises, commonly known as a Blue Moon. The Moon will not actually be the colour blue, so don’t be disappointed.

The definition of this Ble Moon is that it is the second Full Moon to occur in a month. It takes our Moon about 29.5 days to complete one cycle of phases (from New Moon to New Moon), so if a Full Moon occurs on the first of a month, there will be a second Full Moon, a Blue Moon, at the end of the month, too. Hence, the saying “Once in a Blue Moon” (meaning something that occurs rarely).

The moon will reach maximum fullness at 11:45 AM Greek Local Time, but as it will be daytime, and the Moon will be below the horizon, it will be out of sight. However, it will still be lovely, full and bright to the naked eye, throughout the nights of May 30 and May 31.