Wednesday will see a “super blue moon,” a rare combination of two lunar events that will bring the second full moon of August and the year’s biggest and brightest moon to the night sky. The last super blue moon occurred in 2009.
August’s supermoon will appear above the horizon in Mexico after 7 p.m. and travel across the sky from east to west, setting at sunrise.
A blue moon refers to the appearance of a second full moon in a calendar month. According to NASA, they happen every two to three years because the time it takes for the moon to orbit Earth is slightly shorter than a month. The last blue moon was seen on Aug. 21, 2021.
The rarity of the 13th full moon of the year inspired the phrase “once in a blue moon.”
But don’t be disappointed if the moon doesn’t turn blue: on rare occasions, the moon can appear blue to our eyes if it is seen through smoke, but expect it to appear its normal color tonight.
A supermoon happens when the perigee – the point of the lunar orbit at which the moon is closest to Earth – coincides with the full moon phase, an event that happens three to four times a year. According to NASA, a super moon appears about 7% larger than a regular full moon.
The combination of the blue moon and supermoon happening together occurs about every 10 years, and won’t happen again until 2037.