Volume: 06, Issue: 03 03/12/2008 
Path of the Moon through Earth's umbral and penumbral shadows during the Total Lunar Eclipse of February 20, 2008. (Eastern Standard Time) Image credit: NASA.
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This image was taken at 9:36 p.m. EST on February 20 from Buffalo, New York, by an amateur photographer and astronomer. Image Credit: James M. Hudson (Used with the artist's permission).
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The last bit of light creeping away as the Moon slips completely into the heart of the Earth's shadow during the Lunar Eclipse on August 28, 2007. It was taken by Brian Karczewski of Hemet, California. Image credit: Brian Karczewski/SpaceWeather.com.
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Other Articles in This Issue:
Endeavour Soars into Space
Cassini Spacecraft to Dive Into Water Plume of Saturn Moon
Saturn's Moon Rhea Also May Have Rings
Discuss the Martian Surface with Suniti Karunatillake
 

Total Lunar Eclipse

A total eclipse of the Moon occurred during the night of Wednesday, February 20, 2008. The entire event was visible from South America and most of North America (on February 20) as well as Western Europe, Africa, and western Asia (on February 21). During a total lunar eclipse, the Moon's disk can take on a dramatically colorful appearance from bright orange to blood red to dark brown and (rarely) very dark gray.

An eclipse of the Moon can only take place at Full Moon, and only if the Moon passes through some portion of Earth's shadow. The shadow is actually composed of two cone-shaped parts, one nested inside the other. The outer shadow or penumbra is a zone where Earth blocks some (but not all) of the Sun's rays. In contrast, the inner shadow or umbra is a region where Earth blocks all direct sunlight from reaching the Moon. If only part of the Moon passes through the umbra, a partial eclipse is seen. However, if the entire Moon passes through the umbral shadow, then a total eclipse of the Moon occurs.

From start to finish, February's lunar eclipse lasted about three hours and twenty-six minutes (not including the penumbral phases which are very difficult to see). The partial eclipse began as the Moon's eastern edge slowly moved into the Earth's umbral shadow. During the partial phases, it took just over an hour for the Moon's orbital motion to carry it entirely within the Earth's dark umbra. The color and brightness of the totally eclipsed Moon can vary considerably from one eclipse to another. Dark eclipses are caused by volcanic gas and dust which filters and blocks much of the Sun's light from reaching the Moon. But since no major volcanic eruptions have taken place recently, the Moon took on a vivid red or orange color during the total phase. After the total phase ended, it was once again followed by a partial eclipse as the Moon gradually left the umbral shadow.

The total phase of a lunar eclipse is called totality. At this time, the Moon was completely immersed within the Earth's dark umbral shadow. During the February 20 eclipse totality lasted just under 50 minutes. This is quite a bit less than the last total lunar eclipse (August 28, 2007) which lasted 90 minutes.

February's lunar eclipse was well-placed for North and South America as well as Europe and Africa. Observers along North America's west coast missed the early stages of the partial eclipse because it began before the moon rose. Alaskans in Anchorage and Fairbanks experienced moonrise during totality but bright evening twilight made it difficult for sourdoughs to view the event. Western Europe and northwest Africa also saw the entire eclipse. Further to the east (east Africa and central Asia), the Moon set before the eclipse ended. None of the eclipse was visible from eastern Asia or Australia.

Preceding and following the eclipse were hour-long penumbral phases but these are faint and quite difficult to see. The more interesting and photogenic partial and total phases always take center stage to the penumbral phases.

Unlike solar eclipses, lunar eclipses are completely safe to watch. Protective filters are not necessary and neither is a telescope. A lunar eclipse can be observed with nothing more than the naked eye. However, a pair of binoculars magnifies the view and makes the red coloration brighter and easier to see. A standard pair of 7 x 35 or 7 x 50 binoculars is sufficient.

During the eclipse, the Moon was in Leo. Saturn and bright star Regulus were only 3 degrees east and west, respectively, of the Moon. Gemini, Orion, Taurus, and other winter constellations occupied the south and western sky for North American eclipse viewers.

Although total eclipses of the Moon are of limited scientific value, they are remarkably beautiful events. They help to cultivate children’s interest in science and astronomy and to provide a unique learning opportunity for families, students, and teachers. To the nature-lover and naturalist, the lunar eclipse can be appreciated and celebrated as an event which vividly illustrates our place among the planets in the solar system. The three dimensional reality of our universe comes alive in a graceful celestial ballet as the Moon swings through the Earth's shadow.

During the five millennium period from 2000 BC through AD 3000, there are 7,718 eclipses of the Moon (including both partial and total eclipses). From 0 to 3 lunar eclipses (partial or total) occur each year. The last time three total lunar eclipses occurred in one calendar year was in 1982. On average, partial eclipses slightly outnumber total eclipses by 7 to 6.

North Americans will have their next opportunity to see a total lunar eclipse on December 21, 2010.

For more information, please visit the following website:
http://eclipse.gsfc.nasa.gov/lunar.html.

    
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