Monday, February 18, 2008

Lunacy

Like a kid's Christmas, anticipation is half the fun.

On Wednesday evening the Moon will slip into total eclipse. Two of my granddaughters, ages six and eight, will be visiting with their parents. A bonfire on the beach, then a little before nine o'clock the Earth's shadow will start nibbling at the bright disk of the Moon. A hour-and-a-half later the Moon will have turned a spooky red (how dark and what color precisely one cannot reliably predict). By midnight it will all be over, with the restored full Moon standing almost directly overhead. And, as a special treat, Saturn and Regulus will be near the eclipsing Moon, excellent background objects by which to measure the Moon's slow slide through shadow.

Here in Exuma we are pretty much perfectly situated for the eclipse. Warm night. Unobstructed view over the sea. An evening event (our friend Mark in Fiji is out of luck; daytime there, with the Moon hidden behind the Earth).

The only uncertainty is the weather. Will we have clouds or clear sky? We are following the weather reports closely.

My task will be to help the two little girls imagine the shadow, which the Earth wears like a long skinny wizard's cap pointing away from the Sun. At the distance of the Moon's orbit, the shadow is about twice as wide as the Moon, tapering to a point about twice that much further again away. The wizard's cap has a name. The name is "night." Night has a shape.