How Eclipse Magnitude Affects What We See From Earth

An eclipse occurs when one object gets between you and another object and blocks your view. We can observe two kinds of eclipses from the earth. One is an eclipse of the moon and the other is an eclipse of the sun.

When there is an eclipse of the moon, or lunar eclipse, the earth comes between the sun and the moon, throwing a shadow across the moon. When there is an eclipse of the sun, the moon passes between the earth and the sun. The moon blocks out the sun’s light and a moon shadow is cast of the earth’s surface. This is a solar eclipse.

Let’s talk about the solar eclipse. The eclipse magnitude is determined by how much of the surface of the sun is blocked by the moon. There are three kinds of solar eclipses: total, partial and annular. A total eclipse completely blocks out our view of the sun. It is seen only from a narrow strip about 150 km wide. If the eclipse is viewed from areas outside of this strip, we see a partial eclipse. An annular eclipse occurs when the moon is so far from the earth that it appears so small and cannot block out much of the sun.

Whether we see a total or a partial eclipse is determined by how much is blocked from our view. The more area that is blocked the greater the magnitude of the eclipse. An eclipse with a magnitude of .92 means the sun is almost totally blocked. In 1980 there was a total eclipse of a .98. It was so dark that birds thought it was night and started returning to their nests.

Even in a total eclipse it is not entirely dark, because some light escapes around the edge of the sun.