An eclipse occurs when some celestial body in the heavens moves into the shadow of another celestial body. Earth has two types of eclipses: a lunar, referring to the moon, and a solar, referring to the sun. These happen when the Sun, Moon, and Earth are all in one straight line. Astronomers call this a syzygy from a Greek word meaning 'to be joined.' The word eclipse comes from a Greek word also, one related to falling, ékleipsis. In ancient times, people made up stories to explain the darkening of the earth. Today scientists use the eclipses to study more about nature.
Solar eclipses occur when the Moon comes between the Earth and the Sun. They are in a straight line. Every year about two -five solar eclipses occur. There are three types of solar eclipses: total, annular and partial.
A total solar eclipse happens when the Moon completely covers the Sun. It can only be seen from a limited area of Earth. From other angles, it would seem to be a partial eclipse. A partial solar eclipse happens when the Moon covers only a part of the Sun. An annular solar eclipse occurs when the Moon sits squarely on top of and in the center of the Sun and appears smaller than the Sun. A bright colored ring appears to surround the Moon. This is the light from the part of the sun not covered by the Moon. It is called annular from the Latin word for ring, annulus. A hybrid solar eclipse can occur when the total eclipse changes to an annular or the reverse partway along the path.
The Moon does not have any light of its own. The only light it gets is what is reflected from the Sun. When the Earth comes between the Sun and the Moon, it blocks the Sun's light from reaching the Moon. This occurrence is called a lunar eclipse.
There are three kinds of lunar eclipses: a total, penumbral and partial. A total lunar eclipse happens when the Earth's shadow completely prevents any light from the Sun from reaching the Moon. The Latin word for shadow, umbra, is used as the scientific term for Earth's shadow. A partial lunar eclipse happens when only a part of the Moon's surface is hidden by the Earth's umbra. When the Sun, Earth and the Moon are in almost a straight line, the outer or lighter part of the Earth's shadow falls on the Moon, either totally or partially. This is called a penumbral eclipse.
Both Earth and the Moon cast three shadows: an umbra, penumbra, and antumbra. The umbra is the dark center part of the shadow. The penumbra is the lighter outer part of the shadow. The antumbra is a lighter shadow appearing at a distance from the object casting the shadow. It appears only if the light source is larger than the object. It is a lighter part of the shadow. Because the Moon is smaller than the Earth, its umbra can cover only a part of the Earth. However, the penumbra, a lighter shadow can cover whole continents. Thus, partial solar eclipses occur in one location much more often than total solar eclipses.
Ancient peoples invented many different reasons for the solar eclipses. They tried to think of a reason why the sun seemed to disappear from the Earth for a while. Some civilizations thought that a mythical creature ate or stole the Sun. Vietnamese people thought that a giant dog ate the Sun. The ancient Chinese believed that a dragon ate it. In Hindu mythology, the god Rahu was beheaded for drinking the nectar of the gods. His head flies off and devours the Sun. Koreans believed that mythical dogs were attempting to steal the Sun. Sometimes the people banged pots and pans loudly to scare off the demons who caused the eclipse.
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