2011-03-18

Full Moon during lunar perigee

Tomorrow night (March 19th), the full Moon will rise and appear a little larger than usual; that's because it will be about 30,000 km (approx. 18,600 mi) closer to Earth during what's called the lunar perigee [Wikipedia: "Orbit of the Moon"].

The Moon's average distance from our lovely blue marble is about 385,000 km. The Moon's perigee tomorrow night will put it only 356,577 km (221,567 mi) away. While this is really only 7% nearer, the Moon will appear 12-14% larger as it passes across the night sky. Making it the perfect night to gaze upwards at our lonely natural satellite.


When the Moon's perigee coincides with a Full Moon or New Moon, it is sometimes called a "Supermoon" [wikipedia]; though that title appears more often in astrology and mass media than it does in scientific discussions.

Tomorrow's event is even more rare as it is the nearest approach of the Moon during its perigee since March 1993. More still, the Spring equinox occurs on Sunday; making this lunar affair almost as much fun as the "Winter solstice lunar eclipse" which happened last December.

So, as you enjoy the night, be sure to look up and appreciate the beauty of another unique astronomical experience.
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