Waitin' for a supermoon

Above: A comparison of last year's "supermoon," on March 19, 2011, with a more average full moon from December 20, 2010. File from Wikimedia Commons.

Cross your fingers for clear skies this Saturday night, when a phenomenon called a "supermoon" should make for some stunning skywatching.

This Saturday evening, the moon turns full at 11:35pm. At midnight, the moon will reach its perigee -- the point at which it is closest to the Earth during its regular orbit of the planet, which takes 29.5 days. Full moon at perigee happens about once every 14 months.

Astronomer Joe Rao writes in the Christian Science Monitor that the best time to see Saturday's supermoon will be right around moonrise (which, here in upstate New York, should be just before 7pm):

For reasons not fully understood by astronomers or psychologists, a low-hanging moon looks incredibly large when hovering near to trees, buildings and other foreground objects. The fact that the moon will be much closer than usual this weekend will only serve to amplify this strange effect.

So, a perigee moon, either rising in the East at sunset or dropping down in the West at sunrise might seem to make the moon appear so close that it almost seems that you could touch it. You can check out this effect for yourself by first noting the times for moonrise and moonset in your area here: http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-year-us