Brightest Moon in 18 Years to Appear Saturday Night

Look up at the sky tonight. Weather permitting, you'll see the moon at its brightest point in almost two decades.

"The last full moon so big and close to Earth occurred in March of 1993," Geoff Chester of the U.S. Naval Observatory told NASA Science News. "I'd say it's worth a look."

The moon is expected to be so bright that some skywatchers have dubbed it a "supermoon." Not only is it a full moon, but the moon is very near to perigee, the point in its orbit that is closest to the blue planet.

"The full moon of March 19 occurs less than one hour away from perigee - a near-perfect coincidence that happens only [every] 18 years or so," Chester added.

According to Space.com's take on the phenomenon, the supermoon will be 14 percent bigger and 30 percent brighter than the usual full moons that are further from earth tend to appear. The site also said that the last time a moon was this bright was in December 2008. That moon was technically hit full moon status when it was four hours away from perigee. However, Satrtuday night's moon will turn full and reach perigee within the same hour.

While this significant moon will be big and bright, ordinary observers might not notice any difference. Space.com said that a full moon "theoretically lasts just a moment, [and] that moment is imperceptible" to the average eye. The difference in the moon's distance from the earth isn't apparent to those looking at the sky directly; it's still about 356,577 km away, but if the clouds clear, the views could be spectacular.

"The best time to look is when the moon is near the horizon," according to NASA Science News. "That is when illusion mixes with reality to produce a truly stunning view."

The coincidence of the full moon will also cause abnormally high and low tides. It's been rumored throughout the blogosphere that these "perigean tides" can be associated with natural disasters, such as the recent earthquake and ensuing tsunamis in Japan. However, NASA pointed out that the last supermoon in March of 1983 and the near-supermoon two years ago both happened without any kind of incident.