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Supermoon Science: What Is A Supermoon Anyway? (PHOTOS)

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WHAT IS A SUPERMOON
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Send us your supermoon photos this weekend!

You can tweet your photos with hashtag #HPsupermoon. Or, you can submit them directly to our "Supermoon 2013" slideshow, which will be featured in our supermoon live blog on the evening of Sunday, July 23.

We'll be collecting user photos from all over, and yours may be featured!

Skywatchers will be treated this weekend to the year's biggest and brightest full moon -- a so-called "supermoon." And that has some people asking:

Um, just what is a supermoon?

In astronomical terms, a supermoon is actually a pretty simple phenomenon. It's when a new or full moon coincides with lunar perigee -- the point at which the moon is closest to Earth in its elliptical orbit around our planet.

The distance between the Earth and the moon varies from 363,104 kilometers (225,623 miles) at perigee to 405,696 kilometers (252,088 miles) at its greatest distance from Earth (a point astronomers call lunar apogee), according to NASA.

Since a supermoon is closer to Earth, it appears bigger and brighter in the night sky. How much bigger and brighter? Up to 13 percent bigger and 30 percent brighter than a full moon that coincides with lunar apogee, a NASA spokesman told The Huffington Post in an email.

Simple enough, right? Yet as is the case with eclipses, solstices, and other celestial phenomena, there are many popular misconceptions about supermoons. Here are five:

MYTH: Supermoons trigger earthquakes. The closer the moon is to Earth, the greater its gravitational pull on our planet. But since the moon is only slightly closer, the increase is inconsequential. Seismologists have found no evidence to support the idea that supermoons heighten seismic activity.

MYTH: Supermoons drive people crazy. Long ago insanity was sometimes blamed on the lunar cycle -- the very word "lunacy" comes from the Latin word for moon. As Thomas Aquinas wrote in the 1200s, "Demons harass men according to the phases of the moon." But he was wrong. In fact, a 1985 study that looked for links between mental illness and the phases of the moon found none, Space.com reported in 2012.

MYTH: Supermoons cause flooding. At perigee, the moon does exert a bit more gravitational pull on the world's oceans -- and this can bring higher-than-normal "perigean tides," according to NASA. But in most places, the moon's gravitational pull at perigee forces tidewaters only a few centimeters higher than their usual levels.

(Myths continue below infographic.)

MYTH: Astronomers live for supermoons. Neither astronomers nor planetary scientists seem to have any particular interest in supermoons. "Most astronomers don't like full moons because the moon is so bright it's hard to see other things in the night sky," according to the NASA spokesperson.

MYTH: Supermoons are most impressive when observed high in the sky. According to NASA, supermoons are most impressive when viewed near the horizon. And for unknown reasons, full moons look especially vivid when seen through trees and other foreground objects.

Can you top last year's supermoon photos? Check out these breathtaking images of the 2012 supermoon:

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Supermoon - Wikipedia, the free encyclopedia

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