A solar eclipse is an event which occurs when the moon’s orbit takes it between the sun and the Earth. The moon’s shadow then falls on the Earth, and blots out the sun. In some cases, this happens totally, where the sun is completely blocked from view. In others, it happens only partially. Another type of eclipse is called an annular eclipse, and there are also events called hybrid eclipses. This will be explained below.
Total Eclipse
This is the most familiar term to non-astronomers, and one which describes a less common type of eclipse. In a total solar eclipse, the sun is totally blocked from view by the moon, and the moon is surrounded by a glowing nimbus of light, which is the remainder of sunlight which travels around the moon. It is not enough to light the skies, and so during a total eclipse, one will notice the birds singing their bedtime songs, crickets will start singing, too, and animals whose routines run according to the cycle of light and dark will either wake up or go to sleep for the duration of the eclipse. It can be quite an eerie experience. In a five thousand year period (2000BCE to 3000CE), the Earth will experience only 3173 total solar eclipses. That is less than one per year. Bearing in mind that a total eclipse is never seen by every region on Earth, this is not a very common event.
Partial Eclipse
A partial eclipse is by far the more common event when talking about solar eclipses. In this case, the sun is only partially obscured by the sun, blocking some light, but not enough to make it seem like dusk. In the same period of five millennia as referred to above, the Earth will experience 4200 partial eclipses.
Annular Eclipse
This is similar to a partial eclipse, in that the sun is not completely blocked by the moon, but is almost hidden, creating an annulus around the moon. This is a crescent-shaped part of the sun which shines out around the moon, hence the term, “annular”. This type of event may only occur 3956 times in the five thousand year period mentioned above, which is more than the number of total eclipses, but less than the number of partial eclipses.
Hybrid Eclipse
When the type of event changes along the path of the eclipse, it is called a hybrid or “oddball” eclipse. This is the least common type of eclipse, occurring only 569 in the five thousand year period. Sometimes the path of the moon’s orbit and that of the Earth are such that a total eclipse can become annular or partial, or all three variants may occur in one event. Then it is termed a hybrid or oddball eclipse.
Predictions
Total: The next total eclipse will occur on the 13th of November 2012, and will be visible to Australia and the South Pacific.
Annular: The next annular eclipse will take place on the 20th of May 2012, and will be visible to China, Japan, Pacific and western USA.
Partial: The next partial eclipse will take place on the 1st of June 2011, and will be visible to eastern Asia, northern North America and Iceland.
Hybrid: The next hybrid eclipse will take place on the 3rd of November 2013, and will be visible across the Atlantic and Central Africa.
Safety
Viewing an eclipse is an exciting new experience, especially for budding astronomers, who may only see their first eclipse in a year’s time. This enthusiasm should be encouraged and offered every opportunity to learn and grow into a hobby or possibly even a career. It must be remembered, though, that the sun’s light can damage the eyes seriously. Looking up directly at an eclipse can cause irreversible harm to the retinas, and may result in blindness. Even looking through the viewfinder of a camera or telescope can have the same effect. When viewing an eclipse, it is recommended that different protective methods of seeing are used. For example, one can use a pinhole projector, solar filtered goggles, welding goggles, or solar filtered lenses for cameras and telescopes.
Sources:
http://www.mreclipse.com/Special/SEprimer.html
http://www.mreclipse.com/Totality2/TotalityCh11.html
http://eclipse.gsfc.nasa.gov/solar.html
