eclipse tonight

**iwishiwasthere** · 03-14-2006, 02:41 PM

For those who enjoy the night skies be sure to look tonight. This is from a friend that teaches at a college and the Huntsville Space and Rocket Center.

On Tuesday, March 14, the Moon will quietly slip into the Earth's outer shadow, known as the penumbra.

The eclipse will already be in progress on Tuesday evening as the Moon rises and ascends the eastern sky.

What to expect

In a penumbral eclipse, no part of the Moon enters the dark umbral shadow of the Earth, so no part of the Moon shows the distinct outline of the Earth's shadow. Since it will pass through the outer extremities of the Earth's shadow, this is a pale eclipse that will dim the Moon's light only slightly. That edge of the Moon passing closest to the much darker umbra may exhibit a sensible darkening. But unless about 70 percent of the Moon's disk is inside of the penumbra it is not likely to become evident to the eye.

Yet, as penumbral eclipses go, this upcoming event will be a rather unusual one.

Two nights before the eclipse, on March 12, the Moon will arrive at the apogee point of its orbit-its farthest distance from the Earth, 252,446-miles (406,278 km) away. So the Moon will appear nearly 7-percent smaller than average.

As a result, when the Moon interacts with the Earth's shadow, it will be just small enough to become completely immersed within the penumbra, and yet will not be large enough to touch the umbra. It will be completely within the penumbral shadow for one hour beginning at 23:18 GMT (5:18 p.m. CST). According to the renowned eclipse calculator, Jean Meeus, this is only one of five such cases that will occur during the 21st century, the next one not until August 29, 2053.

At the time of the darkest phase of the eclipse (23:48 GMT/5:48 p.m. CST), the Moon will be passing through the northern part of the Earth's penumbra, so its lowermost edge will miss touching the umbra by only 120 mi./192 km. For well over an hour before and after this time, the lowermost portion of the Moon should appear noticeably darkened by the dusky penumbral shadow, especially through binoculars and low-power telescopes.