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Types of Lunar Eclipses

Many myths abound about lunar eclipses. For example, some ancient civilizations believed that angry gods caused the lunar eclipse, which meant that war and devastation would soon follow. Today we know that lunar eclipses occur when the Earth comes between the sun and the moon and the moon enters the Earth's shadow. During an eclipse, the Earth's shadow casts a reddish hue across the surface of the moon. There are different types of lunar eclipses that can occur that depend on the positioning of the moon in the Earth's shadow.

The Facts
- Lunar eclipses occur only during full moons. Since the moon's orbit is inclined, or at an angle, to that of the Earth, the moon rarely is in alignment with the sun and the moon on a full moon. During a lunar eclipse, the moon, sun and Earth are aligned, and the Earth casts its shadow over the moon. The Earth's shadow has two parts: the umbra and the penumbra. The umbra is the inner part of the shadow that is uniformly dark. The penumbra is the outer, fuzzy gray parts of the shadow.
Total Lunar Eclipse
- A total lunar eclipse refers to when the moon moves completely into the earth's umbra. During a total eclipse, the moon does not disappear from the sky because a small amount of sunlight is refracted, or bent, through the atmosphere and enters the shadow of the Earth. This refracted sunlight gives the Earth's shadow and the moon a red or crimson coloring. If you view the moon during a total eclipse, you will notice that the Earth's shadow on the moon can appear a bright red-orange color. It can also appear dark-coppery red or brownish gray.
Partial Lunar Eclipse
- Partial lunar eclipses refer to when the moon enters only a portion of the earth's umbra. At this time, the shadowed portion of the moon contrasts with the bright, uncovered portion of the moon. The shadowed part of the moon that enters the Earth's umbra may appear a dark red or rust color or a charcoal gray color. Partial lunar eclipses resemble the before and after phases of total lunar eclipses when the moon first begins to enter the Earth's umbra and when the moon is leaving the Earth's umbra.
Penumbral Lunar Eclipse
- Another type of lunar eclipse is the penumbral lunar eclipse. This refers to when the moon passes through the penumbra part of the Earth's shadow. Since the moon does not enter the Earth's umbra, its surface is shadowed only by the penumbra. Viewers of this type of eclipse will notice only a slight dimming of the moon. If the moon enters less than half of the Earth's penumbra, observers may not even notice that an eclipse is occurring.

Astronomy