Though some observers have expressed excitement over the first “supermoon” sighting of the year on Saturday, the phenomenon is actually not as rare as one might think, NASA Science News reported.
“Supermoons” — or perigee moons, as they’re known in the scientific community — originate when the Moon is at its closest orbital point to Earth, making it appear 30 percent brighter and around 14 percent bigger than the typical full moon. Three of this year’s five expected “supermoons” are expected to occur in consecutive months: July, August and September.
But U.S. Naval Observatory spokesperson Geoff Chester said that, contrary to popular belief, perigee moons and full moons coincide every 13 months and 18 days. Last year, he told NASA, there were actually three “supermoons,” but only one received widespread attention.
That same amount of attention — and possible misinformation — is likely to occur this weekend, he said.
“I guarantee that some folks will think it’s the biggest Moon they’ve ever seen if they catch it rising over a distant horizon,” Chester was quoted as saying. “Because the media will have told them to pay attention to this particular one.”
Popular astrophysicist and Cosmos host Neil DeGrasse Tyson expressed some frustration last June over similar coverage of a “supermoon” event.
“The Moon’s orbit around the Earth is not a perfect circle,” DeGrasse Tyson said at the time. “Sometimes it’s closer, sometimes it’s farther away. Every month, there is a moment when it is closest. Occasionally, that moment when it is closest coincidences with a full moon. People are calling that a super moon, but there’s super half moons. Every month one of those phases is the closest. I don’t hear people saying like ‘super crescent, super half moon.'”
Watch NASA Science News’ video breakdown of the “supermoon” phenomenon, as posted on Friday, below.