Wednesday night's moon was a super blue moon, a phenomenon that won't happen again until the 2030s. A second full moon that occurs within a single month is called a blue moon. They are only blue in name, not colour. According to NASA, the moon's cycle is 29.5 days, so a blue moon occurs every two to three years. About three per cent of full moons are blue moons. A supermoon is the term used when a full moon nears (within a day or so) the point in its elliptical orbit that is closest to the Earth, called the perigee. Because a supermoon is closer to the Earth, it appears about 14 per cent larger and brighter than normal. A quarter of all full moons are supermoons. Both the Aug. 1 and Aug. 30 moons were supermoons because they neared the perigee, so the Aug. 30 moon has been designated a super blue moon. The Aug. 30 supermoon was roughly 357,344 kilometres from Earth, PBS reported. It was about 160 kilometres closer to Earth than the Aug. 1 supermoon. Super blue moons are not as frequent as either supermoons or blue moons. The next super blue moons will occur in January and March 2037, NASA says.
