Why are there eclipses?

Eclipses happen during a game of shadows. As the Earth travels around the sun, and the moon travels around the Earth, the three unavoidably align a few times a year. We know very well the result of this alignment, because either the sun or the moon darken for a few minutes.

There are two kinds of eclipses. In a solar eclipse, the Earth is darkened by the shadow of the moon. In a lunar eclipse, the moon is darkened by the shadow of the Earth.

There are also three kinds of eclipses for each of them. Solar eclipses can be total (the sun gets fully covered by the moon), annular (the sun gets partially covered by the moon, creating a ring around it), or partial (in which the moon covers only a section of the sun). Lunar eclipses can be total (the moon gets fully covered by the shadow of the Earth), partial (in which the shadow of the Earth covers only a section of the moon), or penumbral (in which the indirect shadow of the Earth covers the moon, yet not as fully as other eclipses).

Eclipses do not last long. This is because the moon rotates slowly (once a month) in its own orbit, but the earth moves much faster. The alignment does not last too long. On the bright side, it is a fact that both the earth and the moon revolve in a stable manner which makes eclipses absolutely predictable. There is more than one calendar available. Actually, I'm including one below.

There are two final things you must know about eclipses to end this article: the first one is that it is very dangerous to watch a solar eclipse directly. As a matter of fact, long exposure of sun rays to your eyes can leave you no less than blind; so you must be careful when watching a solar eclipse. The second is that eclipses do not have anything to do with lunar phases. Lunar phases are a different topic.

Eclipses for 2012

According to the NASA, in 2012 there will be four eclipses:

+ There will be an annular solar eclipse on May 20th, which will be mainly visible from Eastern Asia (China, Mongolia, Russia, Korea) to the United States.

+ There will be a partial lunar eclipse on June 20th, which will be mainly visible in Europe and Africa, but it will also include the Middle East.

+ There will be a total solar eclipse on November 13th, but it will not be very visible. It will travel from northern Australia, but then just cover the Pacific ocean.

+ The last one is a penumbral lunar eclipse on November 28th, which will be visible in Western Africa, South America and the Caribbean.

Knowledge + Why?