Every year there are on average four to six so-called “supermoons,” and the fifth and final one of 2014 took place on September 9, the Smithsonian Magazine reports. The term supermoon refers to a full or new moon at perigee, the point in the orbit of the moon at which it is closest to the Earth. There is disagreement in the supermoon community over whether or not the forthcoming October 8 full moon qualifies as a supermoon, but if so, it will technically be an instance of the super-rare Hunter’s Blood Supermoon in eclipse.
Perigee is possible because the moon’s orbit is not perfectly circular, it moves in an egg-shaped orbit around the earth, allowing it to swing closer to us at one point each month. A supermoon transpires when this close approach occurs in conjunction with one of the two lunar phases: full, when the moon is between Earth and the sun, or new, when it’s on the opposite side of the Earth from the sun. To the naked eye, a full moon looks bigger and brighter than usual, is often correlated with larger than normal tides, and is debated to have effects on animal and human behavior. The closest supermoon this year was on August 10, 2014, when the moon was merely 221,765 miles from Earth.
Though the difference between a supermoon and a normal full moon can be difficult to spot, photographers have been making the most of the dramatic natural phenomenon.