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Lunar eclipse

2007 Schools Wikipedia Selection. Related subjects: Space (Astronomy)

   An eclipse refers to the phenomenon of one body passing into the shadow
   cast by another body. In astronomy, the best-known type of eclipse
   occurs whenever the Sun, Earth and Moon line up exactly. If this
   occurrence is at the time of a full moon where the Moon passes through
   the Earth's shadow, it is called a lunar eclipse. The type and length
   of a lunar eclipse depends upon the Moon's location relative to its
   orbital node. If the lining up of the Sun, Moon and Earth occurs at New
   Moon, the event is referred to as a solar eclipse. The next total lunar
   eclipse will take place at 23:22(UT) on March 3, 2007.
   Lunar eclipse
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   Lunar eclipse

Types of lunar eclipses

   Descending node lunar eclipse paths

   A penumbral eclipse occurs when the Moon only passes through the
   Earth's penumbra, the outer portion of the Earth's shadow. The penumbra
   does not cause the noticeable darkening of the Moon's surface (though
   some may argue it turns a little yellow).

   A special type of penumbral eclipse is a total penumbral eclipse. At a
   total penumbral eclipse the Moon is completely in the penumbra of the
   Earth, but not in the umbra. At a total penumbral eclipse the parts of
   the Moon closest to the umbra are a bit darker than the rest of the
   Moon. Total penumbral eclipses are a rare type of lunar eclipse.

   A total lunar eclipse occurs when the Moon travels completely into the
   Earth's umbra, the dark inner portion of the shadow. The Moon's speed
   through the shadow is about one kilometer per second, and the totality
   may last up to nearly 107 minutes. However, the time between the Moon's
   first contact with the shadow and last contact, when it has completely
   exited the shadow, may be up to 6 h 14 min or so. If only part of the
   Moon enters the umbra, it is called a partial lunar eclipse.

   The Moon does not completely disappear as it passes through the umbra
   because of the refraction of sunlight by the Earth's atmosphere into
   the shadow cone. The amount of refracted light depends on the amount of
   clouds or dust in the atmosphere blocking the light. Refracted sunlight
   causes the Moon to glow with a coppery-red hue that varies from one
   eclipse to the next. The following scale was devised by André Danjon
   for rating the overall darkness of lunar eclipses:

          0. Very dark eclipse; Moon almost invisible, especially in
          midtotality
          1. Dark eclipse; gray or brownish coloration; details
          distinguishable only with difficulty
          2. Deep red or rust-colored eclipse, with a very dark central
          part in the umbra and the outer rim of the umbra relatively
          bright
          3. Brick-red eclipse, usually with a bright or yellow rim to the
          umbra
          4. Very bright copper-red or orange eclipse, with a bluish, very
          bright umbral rim

   Because the Moon's orbit around the Earth is inclined 5° with respect
   to the orbit of the Earth around the Sun, lunar eclipses do not occur
   at every full moon. For an eclipse to occur, the Moon must be near its
   orbital node —the intersection of the orbital planes. Passing through
   the shadow at or very close to the node results in a total or partial
   eclipse.

   The relative distance of the Moon from the Earth at the time of the
   eclipse can affect the eclipse's intensity. Specifically, a
   totally-eclipsed Moon being concomitantly at or near apogee will
   lengthen the duration of totality for two reasons: first, the Moon will
   appear to move more slowly across the umbra, and second, the Moon will
   appear smaller as seen from Earth and therefore remain inside the umbra
   longer.
   Lunar nodes

   Every year there are at least two lunar eclipses. If you know the date
   and time of an eclipse, you can predict the occurrence of other
   eclipses using eclipse cycles. Unlike a solar eclipse, which can only
   be viewed in a certain relatively small area of the world, a lunar
   eclipse may be viewed from anywhere on the night side of the Earth. If
   you were on the Moon's surface during a lunar eclipse you would witness
   a solar eclipse, with the Earth passing in front of the Sun.
   Lunar eclipses in 2003Two total lunar eclipses occurred in 2003. The
   eclipse on May 15 grazed the northern edge of the earth's shadow, and
   the eclipse on November 8 grazed the southern edge. These images show
   the eclipse in November was much brighter as the bottom rim of the Moon
   did not darken as much after completely entering the umbra. The color
   and brightness of the Moon during an eclipse varies according to the
   amount of light refracted by the Earth's atmosphere.
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Lunar eclipses in 2003

   Two total lunar eclipses occurred in 2003. The eclipse on May 15 grazed
   the northern edge of the earth's shadow, and the eclipse on November 8
   grazed the southern edge. These images show the eclipse in November was
   much brighter as the bottom rim of the Moon did not darken as much
   after completely entering the umbra. The colour and brightness of the
   Moon during an eclipse varies according to the amount of light
   refracted by the Earth's atmosphere.
   A partial lunar eclipse, 07.09.2006.
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A partial lunar eclipse, 07.09.2006.

Longest total lunar eclipse between 1900 and 2000

   Date           Duration of total phase
   July 16, 2000  1h47m01s
   July 6, 1982   1h46m20s
   July 27, 2018  1h43m34s
   June 26, 2029  1h42m32s
   August 4, 1906 1h41m48s
   July 7, 2047   1h41m29s
   June 25, 1964  1h41m25s
   July 26, 1953  1h41m22s
   June 28, 2001  1h41m16s
   June 15, 2011  1h40m52s
   June 16, 2076  1h40m49s
   August 6, 1971 1h40m04s

   The longest total lunar eclipse between 1000BC and 3000AD took place on
   May 31, 318. Its total phase had a duration of 1h47m14s.

History

   Lunar eclipse of October 2004
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   Lunar eclipse of October 2004

   The earliest recorded lunar eclipse occurred on 19 March 721 BC, as
   described in Ptolemy's Almagest, based on Babylonian sources.

   Ancient Greek astronomers noticed that during lunar eclipses the edge
   of the shadow was always circular; they thus concluded that the Earth
   was spherical.

   In 499, Indian mathematician Aryabhata gave accurate calculations for
   both the solar eclipse and lunar eclipse.

   In 1504, while stranded on Jamaica, Christopher Columbus "predicted" a
   lunar eclipse (actually, he knew from Zacuto's charts that he had
   brought with him that a lunar eclipse was to occur on February 29 of
   that year), thereby intimidating the island's natives into continuing
   to provision him and his men and thus saving them from death by
   starvation.

   The total eclipse on October 27, 2004 occurred during game 4 of MLB's
   World Series. Many people have pointed to this as a portend of victory
   for the Boston Red Sox, who had not won the championship in 86 years,
   and reversing the so-called Curse of the Bambino. The eclipse gave the
   moon a reddish hue (see picture to the right), and this, along with
   Curt Schilling's blood-soaked sock in Game 2, solidified the sign in
   the minds of Red Sox Nation.
   Retrieved from " http://en.wikipedia.org/wiki/Lunar_eclipse"
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