Africa awaits total eclipse of the sun

The elusive solar corona seen during a 1999 eclipse of the sun

By Richard Stenger
CNN

(CNN) -- The first total solar eclipse of the millennium is expected to create a show of darkness and light Thursday over the South Atlantic and parts of Africa, where thousands of tourists and scientists have gathered.

They can anticipate quite a spectacle. When the moon blocks the rays of the sun during totality, those watching in the shadow below will see the sky suddenly darken into twilight, bringing planets and bright stars into view.

Jupiter, Mercury and Venus should make rare daytime appearances. Under the right conditions -- a very dark and cloudless sky -- stars including Capella, Castor, Pollux, Sirius, Betelgeuse, Rigel and others could make cameo showings as well.

The moon's shadow is to become visible from just east of Uruguay, race across the Atlantic at twice the speed of sound, pass over central Africa and Madagascar, and disappear at dusk over the Indian Ocean -- the marathon lasting only three hours.

INTERACTIVE Watch a simulation of the upcoming eclipse (Courtesy: Andrew Sinclair)    What is a solar eclipse? A solar eclipse takes place when the moon passes between the Earth and the sun, causing the lunar shadow to cross our planet at twice the speed of sound. Anyone situated within the darkest central portion of the shadow, the umbra, can see the moon blot out the entire solar disk.

Observing a solar eclipse While you can safely look at a total solar eclipse with the naked eye, precautions must be taken when looking at a partial eclipse. Specialized sun filters or strong welder's glasses can protect the eyes against vision damage. An alternative is to look at the eclipsing sun on a white background, capturing its silhouette as it waxes and wanes through partial or total phases. To do so, aim sunlight through a homemade pinhole camera or something else with a pinprick hole in it. Direct the focused sunlight onto a white background such as a sheet of paper. A third option is to focus the sun's image through reversed binoculars or a reversed telescope onto a light background. DO NOT look directly through the lens.

Those on the ground should see the sun disappear for only a few minutes. The longest eclipse visible in one spot -- a few seconds shy of five minutes -- should be seen from east of the African coast at about 8 a.m. EDT.

People in a much larger region of the world can anticipate seeing a partial solar eclipse, in which the moon blocks only a fraction of the sun's disk. The partial eclipse shadow is to become visible in Brazil, spread over much of the Atlantic and cover much of Africa, as far north as the central Saharan desert.

For viewing the total eclipse, the best places on terra firma are in central Africa, where the eclipse will last four minutes or longer -- more than twice as long as the last total solar eclipse in 1999.

Thousands of amateur and professional eclipse watchers are in the region, but perhaps in smaller numbers than other parts of the world might have attracted. Unrest including civil wars has plagued parts of Angola, Zambia, Zimbabwe and Mozambique for years.

Most of the eclipse chasers have gone to Zambia, which enjoys more political stability than neighboring nations. Hotels have booked up around prime viewing locations, including the capital Lusaka, the Luangwa game reserve and Kafue National Park.

Among the tens of thousands expected to watch the celestial show from Zambia this week is Jay Pasachoff, a leading U.S. eclipse scientist.

During his 32nd solar eclipse observation, the Harvard-trained astronomer is to study the elusive coronal ring, the outer atmosphere of the sun, which can only be seen when the moon blots out the solar disk.

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The red line depicts the path of the total solar eclipse. The yellow grid marks the region that will experience a partial eclipse

Pasachoff says he hopes his research will help solve a burning solar question: Why does the surface of the sun simmer at about 10,800 degrees Fahrenheit (6,000 degrees Celsius), while the outer coronal ring around the sun blazes at 3.6 million degrees Fahrenheit (2 million degrees Celsius)?

Solar eclipses inspired many legends of the ancients, causing birds to roost, planets and stars to appear and the sun to seem to vanish, leaving behind an awesome halo, the corona. Voracious dragons eat the sun. The sun washes itself during its absence. The sun abandons the Earth. The word "eclipse" comes from the Greek word meaning "abandonment."

Whether banging pots, shooting arrows or chanting, the fearful ancients always managed to make the sun return to its normal perch in the sky.

While modern science has debunked such myths, the reverence with which some view the periodic solar event remains. Contemporary eclipse hunters spend lifetimes chasing solar eclipses -- which they describe as addictive experiences unmatched by other phenomena.