Saturday! Up in the sky! It's Supermoon!
Posted May 4, 2012 12:58 p.m. EDT
Updated May 4, 2012 3:23 p.m. EDT
NEW YORK — The biggest and brightest full moon of the year arrives Saturday night as our celestial neighbor passes closer to Earth than usual.
But don't expect any "must-have-been-a-full-moon" spike in crime or crazy behavior. That's just folklore.
Saturday's event is a "supermoon," the closest and therefore the biggest and brightest full moon of the year. At 11:34 p.m., the moon will be about 221,802 miles from Earth. That's about 15,300 miles closer than average.
That proximity will make the moon appear about 14 percent bigger than it would if the moon were at its farthest distance, said Geoff Chester of the U.S. Naval Observatory. The difference in appearance is so small that "you'd be very hard-pressed to detect that with the unaided eye," he said.
The moon's distance from Earth varies because it follows an orbit that is more of an oval than a perfect circle.
Like any full moon, the supermoon will look bigger when it's on or near the horizon rather than higher in the sky, thanks to an optical illusion, Chester noted. The full moon appears on the horizon at sunset. On the East coast, for example, that will be a bit before 8 p.m. Saturday.
"Look off to the east where the moon always rises, and look for the moon rising up over the trees and the houses," advised Tony Rice, a NASA solar system ambassador who works in the Triangle.
The supermoon will bring unusually high tides because of its closeness and its alignment with the sun and Earth, but the effect will be modest, Chester said.
The last supermoon, on March 19, 2011, was about 240 miles closer than this year's will be. Next year's will be a bit farther away than this year's.
But no matter how far away a full moon is, it's not going to make people kill themselves or others, commit other crimes, get admitted to a psychiatric hospital or do anything else that popular belief suggests, a psychologist says.
Studies that have tried to document such connections have found "pretty much a big mound of nothing, as far as I can tell," said Scott Lilienfeld of Emory University.
Lilienfeld, an author of "50 Great Myths of Popular Psychology," said the notion of full moons causing bizarre behavior ranks among the top 10 myths because "it's so widely held and it's held with such conviction."
"It's not a super-big deal," Rice said. "But anything that gets people outside and looking up at the night sky is a pretty big deal."