By Joe Rao
SPACE.com Skywatching Columnist
posted: 24 March 2006
04:09 pm ET
Amateur and professional astronomers from around the world will soon be congregating in parts of Brazil, Africa, and western Asia, to view a total eclipse of the Sun that will take place on Wednesday, March 29. Without a question of doubt, a total eclipse of the Sun is one of the most spectacular natural sights that one can witness.
Only during totality can one observe the pearly white solar corona, as well as the ruddy chromosphere, and prominences – sights that are normally hidden from our view by the brilliant light of the Sun. In addition, darkness similar to 20 or 30 minutes after sundown suddenly falls over the surrounding landscape, allowing the brighter stars and planets to appear while strange and exotic colors rim the horizon.
Contrary to popular belief, a total eclipse of the Sun is not a rare or unusual spectacle.
In fact, over the past 25 years there have been no fewer than sixteen total solar eclipses, an average of one roughly every 18 months. The regions from where the spectacular sight of a totally eclipsed Sun can be seen, however, are strictly confined to a narrow track; the path that the dark central shadow of the Moon (called the “umbra”) traces out over the Earth’s surface. That track may run for thousands of miles, yet may average less than a hundred miles in width. So while the dark lunar shadow might sweep over the Earth twice over a span of just three years, for a specific geographical location, the odds of lying directly in the path of that shadow is very small.
So, if you intend to wait for this, the greatest of celestial road shows to come to your hometown, your wait is likely to be (on average) about 400 years. That is why many dedicated eclipse watchers – sometimes referred to as “umbraphiles” – will literally chase total solar eclipses around the globe. All for the privilege of “basking in the Moon’s shadow” for a few precious minutes
The last time skywatchers had an opportunity to see the Sun in total eclipse was last April when the Moon’s umbra briefly touched the Earth over the south Pacific Ocean during an unusual “hybrid” eclipse. Besides being accessible only to shipboard observers, the maximum length of totality lasted only about 42 seconds. In contrast, this week's eclipse will be far more accessible and totality will last much longer; just over 4 minutes in the Libyan Desert.
- Partial eclipse: The Moon covers only part of the Sun.
- Total eclipse: The Moon covers the entire disk of the Sun along a narrow path across the Earth.
- Annular eclipse: The Moon is too far from Earth to completely cover the Sun. A thin ring of the Sun's disk surrounds the Moon.
Edited by Rykster, 27 March 2006 - 03:52 PM.