Lunar Eclipse

A lunar eclipse is an event in astronomy that occurs when the Earth lies between the Sun and Moon, thus blocking the solar radiation and casting a shadow of the Earth into the Moon's surface. It is also known as an eclipse of the Moon. Lunar eclipse is caused when the Sun, Earth and Moon are aligned in a straight line. This is the reason as to why lunar eclipse always falls on a full moon night, when the Sun and Moon are exactly opposite to each other. Here is some information about the types of lunar eclipses and the frequency of occurrence.

Types of Lunar Eclipse

In order to understand the types of lunar eclipses, let's learn first about the shadow of the Earth. There are two distinctive parts in the Earth's shadow, viz., the umbra and penumbra. The umbra is the darkest in which there is complete concealing of solar radiation; whereas, in the penumbra, there is partial blockage of solar radiation, resulting in subtle darkening. Depending upon the shadow of the Earth that falls on the Moon, astronomers divided lunar eclipse into three different types, namely, penumbral, partial eclipses and total eclipses, which are discussed as follows:

Penumbral Lunar Eclipse
A penumbral lunar eclipse, as the name suggests, occurs when the Moon is positioned in the Earth's penumbra. It is hard to detect by an unaided eye; and is usually viewed with the help of telescope. A total penumbral lunar eclipse is a type when the Moon falls entirely within the penumbral shadow. It occurs rarely and the brightness of the Moon's surface differs from one portion to another; the area of the moon close to umbra is comparatively darker than the remaining portion. About 35 percent of lunar eclipses are of penumbral type.

Partial Lunar Eclipse
A partial lunar eclipse occurs when a portion of the Moon passes the Earth's umbra. A partial lunar eclipse is easily detectable by our naked eye. However, based on the portion of the Moon that passes through the umbra, at times it may be undetectable. In the final stages of a partial lunar eclipse, the shadowed portion of the Moon turns reddish. About 30 percent eclipses are of partial lunar eclipse type.

Total Lunar Eclipse
Total lunar eclipse is an event when the Moon lies exclusively in the Earth's umbra. During the event of total lunar eclipse, the Moon appears vibrant red in color. As per astronomical calculation in relation to the Moon's speed, total lunar eclipse may last for about 107 minutes. Total lunar eclipse occurs when the Moon lies entirely within the umbral shadow; it usually lasts for about an hour. About 35 percent lunar eclipses are of total type.

It is to be noted that unlike solar eclipse, lunar eclipse is safe to view with our naked eyes. On the night of the lunar eclipse, the moon appears extraordinarily bright before and after the eclipse. It is due to the direct reflection of sunlight by the Moon's surface. On an average, there are two events of lunar eclipses per year. There are four occurrences of lunar eclipse in 2009, the first was the penumbral lunar eclipse that occurred on 9th February. The remaining three are set to take place on 7th July, 6th August and 31st December.