July 31, 2023
The moon will appear bigger and brighter Tuesday, when the first of two August supermoons rises in the sky.
A supermoon is a full moon that occurs when the moon is closest to Earth in its orbit. Due to its closer proximity, the moon can appear brighter and slightly larger, though changes may be difficult to detect. The first supermoon of the month will rise Tuesday afternoon and set around 5:11 a.m. Wednesday, Space.com reports. It should be visible in the southeast — especially since the current weather forecast for Philadelphia calls for mostly clear skies.
The following supermoon is due Wednesday, Aug. 30, and since it's the second full moon of the month, it's also a blue moon. This term actually has nothing to do with color — so don't expect a navy or cerulean moon in the sky — but rather frequency.
A blue moon can refer to the second full moon in a calendar month, or the third of fourth full moons in a season. This one is expected to be the "closest, biggest and brightest" supermoon of the year, peaking around 9:36 p.m., according to Old Farmer's Almanac. A closer supermoon isn't due to occur until Nov. 5, 2025.
Blue moons typically happen every two to three years, with the last one occurring Aug. 22, 2021. Actual blue-hued moons are also possible, but they are, as the old adage implies, extremely rare. The moon can appear blue due to certain kinds of clouds, water droplets in the air or particles created by natural catastrophes. An enormous eruption from the Indonesian volcano Krakatoa sparked this phenomenon in 1883, as the resulting ash rose 50 miles into the atmosphere and behaved as a blue filter.