Sunday, November 3, 2013

Gambia had share of ‘rare hybrid solar eclipse’


Photo Credit: Wikipedia
The Gambia experienced a solar eclipse on Sunday which geographers say is a “rare hybrid eclipse”. It lasted for about half an hour (from around 11:45am) in which a ring of sunlight was still visible, giving a partial eclipse.

A hybrid solar eclipse is an unusual eclipse that morphs between a total eclipse – in which the moon completely blots out the sun – and an annular eclipse, in which a ring of sunlight is still visible around the moon, astronomers say.

This year's event is a rare hybrid eclipse, where for part of the event, the sun's light is not completely covered. Such events, called annular eclipses, are dangerous to watch directly, says the National Geographic Centre.

In other parts, the moon's dark shadow glide across the face of the sun on Sunday, November 3, 2013 giving most of equatorial Africa a rare view of a total eclipse, while in North America's east coast and in northern South America, southern Europe, and the Middle East, it gave a partial eclipse. 
One of nature's most striking events, a total solar eclipse only happens when the Earth, sun, and moon align perfectly. That allows the moon to cast its center-most shadow, called the umbra, over the entire face of the solar disk, the National Geographic Centre explains.

The resultant shadow is projected onto a very narrow strip along the surface of the Earth.
Total solar eclipses occur only every few years; the most recent one was on November 12, 2012, over the South Pacific. The next one after this weekend comes in 2015 over the North Atlantic, the Centre projected.

Sunday’s eclipse

The Centre further explains: “On Sunday, over the course of just 3.3 hours, that lunar shadow touches down 620 miles (1,000 kilometers) east of Jacksonville, Florida, at sunrise.

“The path of the totality - where the entire solar disk is covered - then races across the open North Atlantic Ocean and through central Africa until the lunar shadow leaves the Earth's surface in Somalia at local sunset.

“In total the moon's shadow will have traveled along a path approximately 8,450 miles (13,600 kilometers) across the globe. The totality in Gabon will last about a minute, while in Kenya it will be only be a scant 11 seconds long.”

"It is always astonishing to see the moon apparently cut bites out of the sun,” says eclipse expert Jay Pasachoff, Field Memorial professor at Williams College in Massachusetts and a National Geographic explorer who was in Gabon to observe the event.

"And it is a wonder of modern science and mathematics that you can travel halfway around the world, arriving on a normal day with blue sky, but then, on schedule, the lunar silhouette breaks up the sunlight," says Pasachoff

Hybrid eclipse

A solar eclipse occurs when the Earth, moon, and sun line up so that the moon's shadow is cast on the Earth. A total solar eclipse occurs when the sun's entire disk is covered by the moon. During an annular eclipse, the new moon's apparent diameter is still smaller than the visible disk of the sun, making the covered sun appear for a few minutes as a striking annulus (ring).

But the National Geographic Centre says the weekend's celestial alignment is special for astronomers since it is a rare kind of hybrid eclipse - one where it starts as annular and then becomes total.

"A hybrid eclipse is when the moon's shadow doesn't quite reach the Earth at the beginning and end of the eclipse, but it reaches the Earth in the center of its path as the Earth's curvature bulges up to it, so it is a total eclipse there," explains Pasachoff.

"The last hybrid was in 2005 in the middle of the Pacific Ocean and the next won't be until 2023," according to Pasachoff.

Tips about watching

In case you’ve got no prior knowledge of the dangers of watching directly at the sun in future eclipses, astronomers recommend using either a professionally manufactured solar filter in front of a telescope or camera, or eclipse-viewing glasses that sufficiently reduce the sun's brightness and filter out damaging ultraviolet and infrared radiation.  

“Do not look directly at a partial or annular eclipse with your naked eye,” the US space agency NASA advises. “Eye damage can result very quickly and without your awareness from staring at the sun, even when it is partly eclipsed.”

A pinhole projection of a partial eclipse on the ground is safe to watch, the space agency advises.

Projections

The next solar eclipse will occur on April 29, 2014, with the shadow path crossing over Antarctica. A partial eclipse will be visible again from North America on October 29, 2014, astronomers say.

For North Americans, the weekend's eclipse is just the opening act for the big event that comes when a total solar eclipse will cross the United States from Oregon to South Carolina on August 21, 2017, according to geographic think tanks. 

 SOURCE: TNBES and National Geographic Centre

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