Eclipses...

Why do eclipses occur?

The alligment of the Earth, sun and moon causes an eclipse. The two types of eclipses are solar eclipses and lunar eclipses. Lunar eclipses are the ones that happen more often. They happen when the Earth is directly between the sun and the moon. When the moon passes the Earth's shadow, a lunar eclipse happens. A solar eclipse happens when the moon comes directly between the sun and the Earth. For a short period of time, the moon blocks our view of the sun. If you are standing directly in the moon's shadow, or in the umbra, you are experiencing a total eclipse. However, you can also experience a partial eclipse, if you are in the penumbra.





What did ancient people used to think the eclipse was? 

Eclipses were interpreted differently in the ancient times by different people, when humanity didn't have the machinery and the technology to find out the scientific reasons for why eclipses occur. In some places, eclipses were viewed as evil omens. For example, when the Athenians were planning to abandon Syracuse, they couldn't, because a lunar eclipse scared them immensely. This led to their defeat by the Syracusans.  In the Chinese culture, people believed a ruthless snake attacked their sun. However, some people didn't fear the eclipses. People who built the Stonehenge probably looked at eclipses as a natural phenomenon, and did calculations of both solar and lunar eclipses.



Which type of eclipse occurs most often?  Why?  Are eclipses seen from every point on Earth?

The eclipse that happens more often is the lunar eclipse, and the lunar eclipse can be seen by everyone on the night side of the Earth, while the solar eclipses can only be seen if you are standing in the umbra or penumbra of the eclipse. Solar eclipses are VERY rare, they only happen every6 months or so.

The next eclipse is predicted to happen on June 1st, and it will be a partial solar eclipse.

Now, you may wonder how you should observe an eclipse, and if they are dangerous. Yes, eclipses are dangerous for a few reasons. Firstly, you should never look directly at the sun, because your eyes could be severely damaged from the UV rays. The sun's rays are very strong and in very severe cases, if you look at an aclipse for too long you can lose your eyesight. Below you can find a safe way to look at an eclipse, and you can make the pinhole projector yourself!

WARNING!

Permanent eye damage can result from looking at the disk of the Sun directly, or through a camera viewfinder, or with binoculars or a telescope even when only a thin crescent of the Sun or Baily's Beads remain. The 1 percent of the Sun's surface still visible is about 10,000 times brighter than the full moon. Staring at the Sun under such circumstances is like using a magnifying glass to focus sunlight onto tinder. The retina is delicate and irreplaceable. There is little or nothing a retinal surgeon will be able to do to help you. Never look at the Sun outside of the total phase of an eclipse unless you have adequate eye protection.

Once the Sun is entirely eclipsed, however, its bright surface is hidden from view and it is completely safe to look directly at the totally eclipsed Sun without any filters. In fact, it is one of the greatest sights in nature.

There are five basic ways to observe the partial phases of a solar eclipse without damage to your eyes. We will describe each of them below. We'll also explain how to safely watch an eclipse with binoculars or a telescope.

The Pinhole Projection Method

One safe way of enjoying the Sun during a partial eclipse--or anytime--is a "pinhole camera," which allows you to view a projected image of the Sun. There are fancy pinhole cameras you can make out of cardboard boxes, but a perfectly adequate (and portable) version can be made out of two thin but stiff pieces of white cardboard. Punch a small clean pinhole in one piece of cardboard and let the sunlight fall through that hole onto the second piece of cardboard, which serves as a screen, held below it. An inverted image of the Sun is formed. To make the image larger, move the screen farther from the pinhole. To make the image brighter, move the screen closer to the pinhole. Do not make the pinhole wide or you will only have a shaft of sunlight rather than an image of the crescent Sun. Remember, this instrument is used with your back to the Sun. The sunlight passes over your shoulder, through the pinhole, and forms an image on the cardboard screen beneath it. Do not look through the pinhole at the Sun.

Solar Filters

A second technique for viewing the Sun safely is by looking at it directly through a specially designed solar filter. Such filters permit only a miniscule fraction of the Sun's light to pass through them. Advertisements for solar filters may be found in popular astronomy magazines.

**info from http://www.mreclipse.com/Totality/TotalityCh11.html Check it out if you want to learn more!