NASA explains that tonight (March 19, 2011) a full Moon of rare size and beauty will rise in the east at sunset – a super “perigee moon” – the biggest in almost 20 years:
“The last full Moon so big and close to Earth occurred in March of 1993,” says Geoff Chester of the US Naval Observatory in Washington DC. “I’d say it’s worth a look.”
Full Moons vary in size because of the oval shape of the Moon’s orbit. It is an ellipse with one side (perigee) about 50,000 km closer to Earth than the other (apogee): diagram. Nearby perigee moons are about 14% bigger and 30% brighter than lesser moons that occur on the apogee side of the Moon’s orbit.
…The best time to look is when the Moon is near the horizon. That is when illusion mixes with reality to produce a truly stunning view. 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. On March 19th, why not let the “Moon illusion” amplify a full Moon that’s extra-big to begin with? The swollen orb rising in the east at sunset may seem so nearby, you can almost reach out and touch it.
You watch the explanation on YouTube and read about the full moon on Wikipedia, where names listed for this month’s moon include Crow Moon, Crust Moon, Sugar Moon, Sap Moon, Chaste Moon and (sadly appropriate) Death Moon.
Step out, look up, breathe.