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SCIENCE, SOCIOLOGY, RELIGION => Science and Technology => Topic started by: Tracey on November 07, 2003, 10:07:14 PM

Title: Nov. 8 Total Lunar Eclipse
Post by: Tracey on November 07, 2003, 10:07:14 PM
Overview of Nov. 8 Total Lunar Eclipse

By Joe Rao
Night Sky Columnist

Skywatchers across most of the Americas as well as much of Europe and Africa will have their second opportunity in 2003 to view of one of nature's most beautiful spectacles: A total eclipse of the Moon.

The eclipse occurs Saturday night, Nov. 8 in the Americas and early the next morning in Europe and elsewhere.

Viewers especially in the eastern United States, many of whom were stymied by clouds during a sister event May 15, will be given another chance to see the Moon immersed completely within the Earth’s shadow.

Easy to see

Unlike a total eclipse of the Sun, which requires most people to make a long journey to get into the path of totality, those of the Moon can usually be observed from one's own backyard. The passage of the Moon through the Earth's shadow is equally visible from all places within the hemisphere where the Moon is above the horizon.

Weather permitting, the total phase of the November eclipse will be visible across much of North America, all of South America, as well as all of Europe and Africa and the western half of Asia. That's a potential viewing audience of nearly 3 billion people.

There is nothing complicated about viewing this celestial spectacle. Unlike an eclipse of the Sun, which necessitates special viewing precautions in order to avoid eye damage, an eclipse of the Moon is perfectly safe to watch. All you'll really need are your eyes, but binoculars or a telescope will give a much nicer view.

The eclipse will actually begin when the Moon enters the faint outer portion, or penumbra, of the Earth's shadow more than an hour before it begins moving into the dark inner shadow, called the umbra. The penumbra, however, is all but invisible to the eye until the Moon becomes deeply immersed in it. Sharp-eyed viewers may get their first glimpse of the penumbra as a faint "smudge" on the left part of the Moon's disk at or around 23:09 GMT, which corresponds to 6:09 p.m. EST or 5:09 p.m. CST.

The most noticeable part of this eclipse will come when the Moon begins to enter the Earth’s umbra. A small scallop of darkness will begin to appear on the Moon's left edge at 23:32 GMT, or 6:32 p.m. EST, 5:32 p.m. CST.

The Moon is expected to take 3 hours and 33 minutes to completely pass through the umbra.

While much of the eastern and central portions of the U.S. and Canada will be able to see the Moon enter the umbra, those living to the west of a line running from roughly Corpus Christi, Texas to Medicine Hat, Alberta, Canada will see the Moon rise already in eclipse. So for observers across the western-third of the United States and Canada, a peculiar crescent or notched Moon will appear to rise opposite to the setting Sun.

Eclipse timing

Along the immediate Pacific coast of central California, the Moon rises just a scant several minutes before the onset of the total eclipse. Yet, because of low altitude and bright evening twilight, local observers may not see much of the Moon at all until it begins to emerge from out of the Earth’s shadow.

Conversely, the Moon will be setting in total eclipse across portions of east central Asia and westernmost portions of China and India. Because of low altitude and bright morning twilight, observers in these locations may not see much of the Moon at all after it slips completely into the Earth’s shadow.

The total phase of the eclipse will be unusually short as lunar eclipses go, lasting just 25 minutes and beginning at 1:06 GMT (early on the morning of Nov. 9), corresponding to 8:06 p.m. EST (on Nov. 8) or 5:06 p.m. PST. The Moon will just barely slip through the southern portion of the Earth’s umbra. In fact, at mid-eclipse the southernmost edge of the Moon is tucked inside of the umbra by less than 50 miles.

Already Underway  
In eastern U.S. and Canada, the total portion of the eclipse will be visible for its entire duration. Below, for 11 selected North American cities, the time of local moonrise and the percentage of the Moon’s diameter already immersed in the Earth’s umbra:

Location Moonrise Eclipsed
Edmonton, Alberta
4:45 p.m.
Denver, Colorado
4:47 p.m.
Great Falls, Mont.
4:55 p.m.
Calgary, Alberta
4:56 p.m.
Albuquerque, N.M.
5:02 p.m.
Boise, Idaho
5:24 p.m.
Las Vegas, Nevada
4:35 p.m.
Seattle, Wash.
4:39 p.m.
San Diego, Calif.
4:50 p.m.
Los Angeles, Calif.
4:52 p.m.
San Francisco, Calif.
5:02 p.m.

During totality, although the Moon will be entirely immersed in the Earth’s shadow, it likely will not disappear from sight. Rather, it should appear to turn a coppery red color, a change caused by the Earth's atmosphere bending or refracting sunlight into the shadow.

Since the Earth's shadow is cone-shaped and extends out into space for some 857,000 miles (1,379,000 kilometers) sunlight will be strained through a sort of "double sunset," all around the rim of the Earth, into its shadow and then onto the Moon. So, unless airborne volcanic aerosols or other atmospheric effects influence its appearance, the Moon’s disk should remain relatively bright, especially right along its southern rim.

This eclipse has all the makings of being a rather colorful event.

For Europe and Africa, the mid-point of this eclipse occurs within about an hour or two after local midnight on Nov. 9, and the Moon will be very well placed in the south-southwest sky.

At the moment of mid-totality (1:19 GMT, or 8:19 p.m. EST), the Moon will stand directly overhead from a point in the Atlantic Ocean just off of the coast of Senegal. The closer an observer is to this region, the higher in the sky the Moon will be.

From London, the Moon will stand 50 degrees above the horizon and for Paris, the Moon’s altitude will be a trifle higher at 51 degrees (10 degrees is roughly equal to the width of your fist held at arm’s length).

The Moon will pass entirely out of the Earth's umbra at 3:05 GMT, or 10:05 p.m. EST, and the last evidence of the penumbra should vanish at or around 3:28 GMT (10:28 p.m. EST.)

The next total lunar eclipse will be on May 4 of 2004 and will favor Eastern Europe, central and eastern Africa and western portions of Asia. The next total lunar eclipse that will be readily available to North Americans will occur just about a year from now, on the night of Oct. 27-28, 2004.