Why the total eclipse of the moon was red

Here it is, Rich.

From: Yahoo News

Amazing Spectacle: Total Lunar Eclipse Monday Night

For a few hours on the night of Dec. 20 to Dec. 21, the attention of tens of millions of people will be drawn skyward, where the mottled, coppery globe of our moon will hang completely immersed in the long, tapering cone of shadow cast out into space by our Earth. If the weather is clear, favorably placed skywatchers will have a view of one of nature’s most beautiful spectacles: a total eclipse of the moon. …

Color and brightness in question

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 about 844,000 miles (1,358,000 km), 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.

However, because of the recent eruptions of the Eyjafjallajökull volcano last spring and the Merapi volcano in Indonesia in October, one and possibly even two clouds of ash and dust might be floating high above the Earth.  As a result, the moon may appear darker than usual during this eclipse; during totality, parts of the moon might even become black and invisible.

A careful description of the colors seen on the totally eclipsed moon and their changes is valuable.  The hues depend on the optical equipment used, usually appearing more vivid with the naked eye than in telescopes.  The French astronomer Andre-Louis Danjon introduced the following five-point scale of lunar luminosity (“L”) to classify eclipses:

L = 0:  Very dark eclipse, moon almost invisible, especially in mid-totality.

L = 1:  Dark eclipse, gray or brownish coloration, details distinguishable only with difficulty.

L = 2:   Deep red or rust-colored eclipse, with a very dark central part in the shadow, and outer edge of the umbra relatively bright.

L = 3:   Brick red eclipse, usually with a bright or yellow rim to the shadow.

L = 4: Very bright copper-red or orange eclipse, with a bluish very bright shadow rim.

Examine the moon at mid-totality and also near the beginning and end of totality to get an impression of both the inner and outer umbra.  In noting an L observation, state the time and optical means (naked eye, binoculars or telescope) that is used.  We invite readers to e-mail their Danjon estimate for this eclipse (along with any pictures they’d like to share) to cmoskowitz-at-SPACE.com.

At mid-totality, from rural locations far from city lights, the darkness of the sky is impressive.  Faint stars and the Milky Way will appear, and the surrounding landscape will take on a somber hue.  As totality ends, the eastern edge of the moon begins to emerge from the umbra, and the sequence of events repeats in reverse order until the spectacle is over.

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