PRAGUE, March 28, 2006 (RFE/RL) -- A total solar eclipse happens when the moon passes directly between our planet and the sun, as seen from a particular place on Earth.
For a few minutes of "totality," the sun appears to be blotted out. And so for those in its path, the eclipse promises a spectacle -- weather permitting, of course.
"What you would see is a sort of halo of light around the sun," says Apostolos Christou, a research astronomer at Armagh Observatory in Northern Ireland.
"This is called the solar corona, it's made up of streams of particles that emanate from the sun," he continues. "That's usually quite bright in absolute terms, but we can't really see it most of the time because the disc of the sun is so much brighter. You would probably also see some of the brightest stars and planets that happen to be on the sky at that time."
On average, any one spot on Earth will see a total eclipse only rarely -- perhaps once every hundred years or so, though occasionally, two consecutive eclipses will cross paths at the same place.
But total eclipses are actually fairly common overall, with one visible somewhere on earth every couple of years.
So the era of modern travel has given rise to a new breed of eclipse enthusiasts. "Eclipse chasers," as they're known, travel the world to catch a glimpse.
Take Olivier Staiger, a Swiss limousine driver. He's now in Egypt to see his 10th total eclipse. Every one is different, he says. And he remembers his first, in November 1994, as being "like a first love."
"So I went to Brazil, the fantastic waterfalls of Iguacu was one of the places where you could see it," he says. "And I saw it, it was really overwhelming. I was on my knees and whispering, 'Oh, my God.' This was really a breathtaking and stunning event. And that was where I decided to travel and see other ones."
It's not surprising then, that countries along the eclipse path are taking advantage of this opportunity. Libya, Egypt, Turkey, and the Greek island of Kastellorizo have all drawn thousands of tourists for the event.
But aside from the spectacle and the tourist dollars, solar eclipses are of scientific value, too.
"Nowadays, the eclipse can be used to study more about its effects on the Earth and its atmosphere rather than [to study] the sun itself, which was the historical importance of them," says Andrew Norton, who teaches astronomy at the Open University in the United Kingdom.
He says scientists, for example, can use the total eclipse to study so-called "shadow bands."
"Shadow bands is a sort of optical interference effect just before and just after the total eclipse, when you have a narrow edge of the sun visible," Norton says. "This narrow source of light can give you this optical interference effect where you get very faint alternating bands of bright and darkness that chase across the landscape as the eclipse moves. Studying those can tell you about the structure of the Earth's atmosphere and the movement of pockets of air of different temperatures in the atmosphere."
Aside from those able to see the total eclipse, a partial eclipse will be visible along a much broader area in Africa, Europe, and Central Asia.
But for anyone planning to watch on March 29, a word of warning from Armagh Observatory's Christou: "Don't forget -- never view the sun without the appropriate filters. You watch a solar eclipse with an unaided eye at the wrong time for one second [and] you're blind."
It's safe to look when the sun is completely blotted out. That part -- "totality" -- will last anywhere from one to four minutes, so for those in the right place, there should be enough time to enjoy the eclipse without risking your eyesight.
For a few minutes of "totality," the sun appears to be blotted out. And so for those in its path, the eclipse promises a spectacle -- weather permitting, of course.
"What you would see is a sort of halo of light around the sun," says Apostolos Christou, a research astronomer at Armagh Observatory in Northern Ireland.
"This is called the solar corona, it's made up of streams of particles that emanate from the sun," he continues. "That's usually quite bright in absolute terms, but we can't really see it most of the time because the disc of the sun is so much brighter. You would probably also see some of the brightest stars and planets that happen to be on the sky at that time."
On average, any one spot on Earth will see a total eclipse only rarely -- perhaps once every hundred years or so, though occasionally, two consecutive eclipses will cross paths at the same place.
But total eclipses are actually fairly common overall, with one visible somewhere on earth every couple of years.
So the era of modern travel has given rise to a new breed of eclipse enthusiasts. "Eclipse chasers," as they're known, travel the world to catch a glimpse.
Take Olivier Staiger, a Swiss limousine driver. He's now in Egypt to see his 10th total eclipse. Every one is different, he says. And he remembers his first, in November 1994, as being "like a first love."
"So I went to Brazil, the fantastic waterfalls of Iguacu was one of the places where you could see it," he says. "And I saw it, it was really overwhelming. I was on my knees and whispering, 'Oh, my God.' This was really a breathtaking and stunning event. And that was where I decided to travel and see other ones."
It's not surprising then, that countries along the eclipse path are taking advantage of this opportunity. Libya, Egypt, Turkey, and the Greek island of Kastellorizo have all drawn thousands of tourists for the event.
But aside from the spectacle and the tourist dollars, solar eclipses are of scientific value, too.
"Nowadays, the eclipse can be used to study more about its effects on the Earth and its atmosphere rather than [to study] the sun itself, which was the historical importance of them," says Andrew Norton, who teaches astronomy at the Open University in the United Kingdom.
He says scientists, for example, can use the total eclipse to study so-called "shadow bands."
"Shadow bands is a sort of optical interference effect just before and just after the total eclipse, when you have a narrow edge of the sun visible," Norton says. "This narrow source of light can give you this optical interference effect where you get very faint alternating bands of bright and darkness that chase across the landscape as the eclipse moves. Studying those can tell you about the structure of the Earth's atmosphere and the movement of pockets of air of different temperatures in the atmosphere."
Aside from those able to see the total eclipse, a partial eclipse will be visible along a much broader area in Africa, Europe, and Central Asia.
But for anyone planning to watch on March 29, a word of warning from Armagh Observatory's Christou: "Don't forget -- never view the sun without the appropriate filters. You watch a solar eclipse with an unaided eye at the wrong time for one second [and] you're blind."
It's safe to look when the sun is completely blotted out. That part -- "totality" -- will last anywhere from one to four minutes, so for those in the right place, there should be enough time to enjoy the eclipse without risking your eyesight.
