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Old Tuesday, June 16, 2009
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Default Lunar and Solar Eclipse

Eclipse:
Eclipse, in astronomy, the obscuring of one celestial body by another, particularly that of the sun or a planetary satellite. Two kinds of eclipses involve the earth: those of the moon, or lunar eclipses; and those of the sun, or solar eclipses.


Lunar eclipse


A lunar eclipse occurs when the earth is between the sun and the moon and its shadow darkens the moon.
The earth, lit by the sun, casts a long, conical shadow in space. At any point within that cone the light of the sun is wholly obscured. Surrounding the shadow cone, also called the umbra, is an area of partial shadow called the penumbra.
A lunar eclipse can only occur at Full Moon and only if the Moon passes through some portion of Earth's shadow. That shadow is which is composed of two cone-shaped components, one nested inside the other. The outer or penumbral shadow blocks part but not all of the Sun's rays from reaching the Moon. In contrast, the umbral shadow blocks all direct sunlight from reaching the Moon.


There are three types of lunar eclipses
1. Penumbral Lunar Eclipse:
It occurs when the moon passes through Earth's penumbral shadow. These events are subtle and hard to observe.
2. Partial Lunar Eclipse:
It occurs when a portion of the moon passes through Earth's umbral shadow. These events are easy to see, even with the unaided eye.
3. Total Lunar Eclipse:
Total Lunar eclipse takes place when the entire moon passes through Earth's umbral shadow. These events are quite striking due to the Moon's vibrant red color during the total phase i.e. totality.


Solar Eclipse


A solar eclipse occurs at New Moon when the Moon passes between Earth and Sun. If the Moon's shadow happens to fall upon Earth's surface at that time, some portion of the Sun's disk covered or eclipsed by the Moon. The solar eclipse doesn’t occur frequently as the Moon's orbit around Earth is tilted 5 degrees to Earth's orbit around. As a result, the Moon's shadow usually misses Earth as it passes above or below earth at New Moon. At least twice a year, the geometry lines up just right so that some part of the Moon's shadow falls on Earth's surface and an eclipse of the Sun is seen from that region.
When the Moon's penumbral shadow strikes Earth, we see a partial eclipse of the Sun from that region. Partial eclipses are dangerous to look at because the un-eclipsed part of the Sun is still very bright.


The three types of solar eclipses are
1. Partial Eclipse:
A partial eclipse occurs when the Sun and Moon are not exactly in line and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of the Earth outside of the track of an annular or total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbra never intersects the Earth's surface.
2. Annular Eclipse:
An annular eclipse occurs when only a small, ring-like sliver of light is seen from the sun's disc. the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon.
3. Total Eclipse:
A total eclipse occur when the entire central portion of the sun is blocked out. During any one eclipse, totality is visible only from at most a narrow track on the surface of the Earth.

Last edited by Princess Royal; Tuesday, June 16, 2009 at 12:46 PM.
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