Monday, December 20, 2010

Total lunar eclipse for the winter solstice tomorrow

A lunar eclipse occurs when the moon passes behind the earth
so that the earth blocks the sun’s rays from striking the moon.
This can occur only when the Sun, Earth and Moon are aligned exactly,
or very closely so, with the Earth in the middle.

From MrEclipse

A total
eclipse of the Moon occurs during the early morning hours of December 21, 2010 (for observers in western North America and Hawaii, the eclipse actually begins on the evening of December 20).
The entire event is visible from North America, Greenland and Iceland.
Western Europe will see the beginning stages of the eclipse before moonset while western Asia will get the later stages after moonrise.
During a total lunar eclipse, the Moon's disk can take on a dramatically colorful appearance from bright orange to blood red and more rarely dark brown to very dark gray.

One of the great things about lunar eclipses is that they are completely safe to view with the naked eye.
No special filters are required to protect your eyes like those used for solar eclipses.
You don't even need a telescope to watch the eclipse although a good pair of binoculars will help.

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.
One is reminded that Christopher Columbus got out of some difficulty with Native Americans when, knowing that a lunar eclipse was coming, threatened to take the moon away.

Then only part of the Moon passes through the umbra, a partial eclipse is seen.
If the entire Moon passes through the umbral shadow, then a total eclipse of the Moon occurs.
It is also possible to have an eclipse where the Moon passes through only the penumbra.
Each of these eclipses has a unique and distinct appearance (see
Visual Appearance of Lunar Eclipses).
For more information on how, what, why, where and when of lunar eclipses, see the special web page
Lunar Eclipses for Beginners.

Links :
  • NASA eclipse website
  • Wired : Lunar eclipse tonight will cast rare shadow on winter Solstice
  • YouTube : I / II

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