OKLAHOMA CITY -- Be prepared to see a full Moon of incredible size and beauty Saturday, March 19, 2011. It's called a super perigee moon, and will be the biggest in almost 20 years.
"The last full Moon so big and close to Earth occurred in March of 1993," Geoff Chester of the US Naval Observatory in Washington DC told NASA's web site. "I'd say it's worth a look."
According to Dr. Tony Phillips at science@NASA, full Moons vary in size because of the Moon's orbit is not a perfect circle around the Earth. NASA says the orbit is an ellipse with one side, called a perigee, about 31,000 miles closer to Earth than the other, called an apogee.
You can view NASA's diagram to understand how the Moon's orbit works.
Perigee moons appear to be about 14 percent bigger and 30 percent brighter than lesser moons that occur on the apogee side of the Moon's orbit.
Dr. Phillips said the best time to look for the super Moon is when the Moon is near the horizon, which is right after sunset. "For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects," wrote Dr. Phillips.