The moon's dark shadow will glide across the face of the sun on Sunday, November 3, giving most of equatorial Africa a rare view of a total eclipse.
Skywatchers living along North America's east coast and in northern South America, southern Europe, and the Middle East, meanwhile, will still glimpse a partial eclipse. (See "Solar Eclipses.")
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 resultant shadow is projected onto a very narrow strip along the surface of the Earth.
This year's event is a rare hybrid eclipse, where for part of the the event, the sun's light is not completely covered. Such events, called annular eclipses, are dangerous to watch directly (learn more about them below).
Weekend Solar Eclipse
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.
Though the most dramatic parts of this celestial phenomenon will only be visible in remote areas of central Africa, armchair astronomers can watch a live webcast of the eclipse by SLOOH.com.
The online observatory will provide multiple feeds beamed from the African continent along the path of totality, including coverage from Kenya, Gabon, and the Canary Islands off the coast of West Africa.
The broadcast will start on November 3, starting at 6:45 am EST (11:45 GMT) and ending at 10:15 am EST (15:15 GMT). (See a list of cities and times.)
North Americans should take note that Daylight Saving Time ends on the same day as the eclipse, at 2 a.m. Sunday morning local time.
"It is always astonishing to see the moon apparently cut bites out of the sun," said eclipse expert Jay Pasachoff, Field Memorial professor at Williams College in Massachusetts and a National Geographic explorer who will be 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."
Watch the eclipse here:
What is special about this eclipse?
As mentioned, a solar eclipse occurs when the Earth, moon, and sun line up so that the moon's shadow is cast on the Earth. (Video: Sun 101.) 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).
This 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."
Only people watching at the very beginning of the eclipse, a few hundred miles out in the Atlantic Ocean east of Bermuda, will see the event when it is annular.
The rest of the eclipse's path, thousands of miles long and including the whole track across Africa, will feature a total eclipse.
So for almost everyone on Earth who is on the narrow path of the moon’s dark shadow, it will be a total solar eclipse on Sunday.
“Only one planeload of people flying out of Bermuda to the transition point between annular and total will actually have a hybrid experience,” said Pasachoff.
Where will the partial eclipse be visible?
Partial phases of the eclipse—where only a percentage of the sun is covered by the lunar disk—will be visible across a much wider area, including the eastern coast of North America, northern South America, southern Europe, and the Middle East.
"The partial phases of the eclipse will be visible from the whole eastern seaboard of the United States, including Puerto Rico, and down to Venezuela and Colombia, and then eastward through all of Africa except its southern tip," said Pasachoff.
"The northern limit will be at the Pyrenees in the south of Spain, the middle of Italy, and the top of Greece."
How much of the show will be visible in North America?
In the United States, the partial eclipse will be visible at sunrise, 6:30 a.m. EST on that day. From Boston to New York, over 50 percent of the sun will be covered by the silhouette of the moon at sunrise, and it will be 47 percent covered in Washington, D.C., and Miami.
In Canada, Halifax gets to see 43 percent of the sun's disk masked, Montreal 32 percent, and Toronto 10 percent.
Roughly 45 minutes later, when the eclipse is about 8 degrees high in the sky (about four fingers high at an outstretched arm), only a tiny bite out of the sun will be left to see.
"So viewers will really want to look between sunrise and about a half hour later, when the sun is only about two fingers high on the east-southeast horizon,” advises Pasachoff.
Where are the best spots to watch from in North America?
The farther east along the continent, the longer the partial eclipse will be visible, as the percentage of the sun's diameter covered by the moon's silhouette varies from about 60 percent down to 0 percent. The entire partial eclipse will last no more than three-quarters of an hour at most.
But to see the largest bite taken out of the sun, you have to see a perfect horizon to the east, without hills or trees, advises Pasachoff. The best locations will overlook the Atlantic Ocean, where visibility is straight down to the horizon.
How far west in North America will the partial eclipse be visible?
"The extreme western limit to catch the eclipse at local sunrise—when just the tiniest bit of the sun will apparently be covered by the lunar silhouette—goes through the middle of Ohio, eastern Kentucky, eastern Tennessee, and eastern Alabama and the Florida Panhandle," said Pasachoff.
How best to watch this event?
For observers along the path of the eclipse, 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. (Check out a DIY alternative: Build an eclipse viewer).
Do not look directly at a partial or annular eclipse with your naked eye, 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.
What if I miss this one?
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.
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.