Lunar Eclipse Essay

2998 Words Feb 18th, 2013 12 Pages
Lunar eclipse

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The June 2011 total eclipse
A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the Sun, Earth, and Moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes. Unlike a solar eclipse, which can only be viewed from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at any given place, due
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The Moon is at its closest to the center of the Earth's umbra. U3 (Fourth contact): End of the total eclipse. The Moon's outer limb exits the Earth's umbra. U4 (Fifth contact): End of the partial eclipse. The Earth's umbra leaves the Moon's surface. P2 (Sixth contact): End of the penumbral eclipse. The Earth's shadow no longer makes any contact with the Moon.

Selenelion

A selenelion or selenehelion occurs when both the Sun and the eclipsed Moon can be observed at the same time. This can only happen just before sunset or just after sunrise, and both bodies will appear just above the horizon at nearly opposite points in the sky. This arrangement has led to the phenomenon being referred to as a horizontal eclipse. There are typically a number of high ridges undergoing sunrise or sunset that can see it. Indeed, the reddened light that reaches the Moon comes from all the simultaneous sunrises and sunsets on the Earth. Although the Moon is in the Earth’s umbra, the Sun and the eclipsed Moon can both be seen at the same time because the refraction of light through the Earth’s atmosphere causes each of them to appear higher in the sky than their true geometric position.[3]

The Moon does not completely disappear as it passes through the umbra because of therefraction of sunlight by the Earth’s atmosphere into the shadow cone; if the Earth had no atmosphere, the Moon would be

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