Supermoon Lights Up Sky, Impresses Skywatchers

Saturday's full moon was the biggest in 18 years.

ByKi Mae Heussner
March 20, 2011, 10:49 AM

March 20, 2011— -- Did last night's rare "supermoon" live up to its hype?

If the commentary online is any indication, those who had clear skies were not disappointed with the brilliant full moon that lit up the sky.

On Twitter, Facebook and Flickr, skywatchers around the world posted pictures and reactions to the the biggest full moon in nearly decades.

During the so-called "supermoon," the moon wasn't just at its closest approach to Earth in its elliptical orbit, it was closer than it has been in 18 years.

After the sun set for East Coasters, #supermoon started trending on Twitter, as people started tweeting about the event. Many even uploaded snapshots of their supermoon views to the photo-sharing website Flickr.

"It's a bird- it's a plane- no, it's Supermoon!," said one Facebook user.

"the supermoon was super beautiful last night," posted another.

The commentary even continued into Sunday morning.

"#supermoon that moon last night was crazy almost thought it was the sun but the sky was black!,'' posted someone on Twitter.

Full moons come in different sizes because of the elliptical shape of the moon's orbit -- one side of the ellipse is about 31,000 miles closer to Earth than the other. When the moon is closest to Earth (at its perigee), it is 14 percent larger and 30 percent brighter than when it's farthest from the planet (at its apogee).

For weeks, Saturday's so-called "supermoon" sparked interest online, with astrologers and amateur astronomers speculating that the extra-large full moon could lead to unusual weather. After Japan's earthquake, some even wondered if the supermoon contributed to the event.

'Supermoon' Not Connected to Earthquakes, Natural Disasters, Scientists Say

In a post earlier this month, Accuweather blogger MarkPaquette said the phrase "supermoon" originated on the website of astrologer Richard Nolle and spread to astronomers online.

According to Nolle's definition, a new or full moon at 90 percent or more of its perigee (or closest approach to Earth) qualifies as a "supermoon."

According to "new age" forecasts, he said, the supermoon brings strong earthquakes, storms or unusual climate patterns.

"There were supermoons in 1955, 1974, 1992 and 2005," Paquette wrote. "These years had their share of extreme weather and other natural events. Is the Super Moon and these natural occurrences a coincidence?"

But scientists emphasize that there is no connection between the moon's position and extreme weather or natural disasters (like Japan's earthquake) here on Earth.

"There's nothing really special about this," NASA astronomer Dave Williams told

The moon orbits the Earth every 29-1/2 days, so it reaches perigee more than once a month. The orbit of the moon changes slightly over time, so the distance between Earth and the moon also changes -- but only slightly, Williams said.

On Saturday, it was probably only about half a percent closer than it ever is every 18 years, he said, which is a "very, very small amount." Even at its closest approach last night, the moon was still about 221,567 miles away, according to NASA.

And though the gravitational effect of the moon causes tides (when the moon is closer, the tides are slightly larger), he said there's "no scientific reason whatsoever" to expect that this supermoon would result in floods or other extreme conditions.

For many, last night's full moon probably didn't even look that different from the average full moon (although scientists say the moon looks larger when it's closer to the horizon).

Still, Williams said, Saturday's full moon was the biggest that you'll ever see.

"You will see this moon again," he said. "But this is as big as it gets."

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