On March 19th, a full Moon of rare size will rise in the east at sunset. It's a "perigee moon" and the biggest in almost 20 years.
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). Perigee moons (closer in orbit) are about 14% bigger and 30% brighter than apogee moons (farther in orbit).
The full Moon of March 19th occurs less than one hour away from perigee--a near-perfect coincidence that happens only every 18 years or so, according to NASA.
A perigee full Moon brings with it extra-high "perigean tides," but this is nothing to worry about, according to NOAA. In most places, lunar gravity at perigee pulls tide waters only an inch or so higher than usual.
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 that looks almost as if you could reach out and touch it.
Don't bother trying though. Even a super perigee Moon is still 356,577 km away. But what a spectacle! :)
Credit: Science@NASA
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