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TRANSPARENT MOON: Have you ever noticed the Moon in broad daylight? The next time you do, look carefully. "The Moon seems strangely transparent," says Sylvain Weiller of St Rémy lès Chevreuse, France, who took this picture on May 20th:
What's happening? The bright blue sky of Earth fills in the Moon's dark seas, tricking your eye, giving the Moon a see-through appearance.
This weekend is a good time to "see through" the Moon. After breakfast on Sunday, step outside and face south. You'll find the fat crescent moon about halfway up the morning-blue sky.
FIREBALL MOVIE: It happens more often than you might think. Every few days or so, somewhere on Earth, a small asteroid will hit the atmosphere producing a fantastic fireball. Astronomers call them "bolides." They cast shadows, let loose a sonic boom, and explode in mid-air.
On May 4, 2006, astronomer Jim Gamble caught one flying over El Paso, Texas:
Click to view the full-sized movie.
Remarkably, most bolides are never noticed by anyone. Some streak over uninhabited oceans and deserts. Others appear during broad daylight when the sun outshines them, or in the deep of night when people are asleep and not looking up.
The May 4th bolide was different. It appeared at 9:45 p.m. local time, well before bedtime, over a densely populated area. Thousands of people saw it. Indeed, how could they miss it? It was brighter than the Moon, which also appears in the video--the stationary light at bottom-right.
Bolides: another good reason to keep looking up.