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CNN Live At Daybreak

The Science Behind a Solar Eclipse

Aired June 21, 2001 - 07:31   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
COLLEEN MCEDWARDS, CNN ANCHOR: The eclipse is coming. The eclipse is coming. And when it does come about an hour from now, it will probably look more or less like this one, when the Earth blots out the sun. We dug this out of our archival tape here at CNN.

But we're going to show it to you when it happens. And we have an expert on solar eclipses joining us right now from the Goddard Space Flight Center in Maryland, NASA astronomer Beth Brown.

Beth, thanks for being here.

BETH BROWN, NASA ASTRONOMER: Thank you.

MCEDWARDS: We're going to try to show our viewers that as it happens in the next hour or so. What should we be watching for?

BROWN: Well, what will happen in a solar eclipse is that the moon will pass directly between the Earth and the sun. And the shadow of the moon will fall across a part of the Earth. And today that will be Africa. And people that are standing in that shadow will see a total solar eclipse of the sun.

MCEDWARDS: OK, now explain -- give us some of the science behind it. First of all, I mean, why are these only visible in certain parts of the world, depending on when they happen?

BROWN: Well, the shadow of the moon is actually very narrow. And so only parts of the Earth at any given time when there's a solar eclipse that's happening will see that solar eclipse. And people outside of that path of totality might see a partial solar eclipse.

MCEDWARDS: Now, astronomers like you study these eclipses for all kinds of things. Explain that.

BROWN: Well, during a solar eclipse, either natural or artificial, we can study the outer parts of the sun -- the hot outer atmosphere that's called the corona.

MCEDWARDS: And what's so interesting about the corona? What do you learn from it?

BROWN: Well, the corona is the source of phenomena such as coronal mass ejections. These massive amounts of material are ejected from the sun and could intercept the Earth and create problems for us down here, such as power failures or disruptions in satellite communications.

MCEDWARDS: You just said something interesting, too. You said when you study eclipses, "either natural or artificial." What's an artificial one?

BROWN: Well, an artificial one, you just saw an image there. And what happens is that we have an instrument on a satellite in space which covers the face of the sun, creating an artificial eclipse.

MCEDWARDS: OK, so that allows you to study more at your own convenience, I guess, than having to wait around...

BROWN: That's right.

MCEDWARDS: ... a few years.

How long -- when the actual darkness happens, how long will it last?

BROWN: Well, for any given person at any given time, it'll last for about 4 1/2 minutes.

MCEDWARDS: And how safe is it to view it during that -- during that period of time?

BROWN: Well, it's only during the time where the moon completely covers the face of the sun that you can see it without the aid of special filters. Otherwise, just as you're trying to look at the natural sun without the eclipse, you need special filters -- special glasses to see that.

MCEDWARDS: And why is that, Beth?

BROWN: Because the sun is extremely bright and we don't want to damage our eyes by looking directly at it.

MCEDWARDS: So the strength of those rays without you being able to squint because they're bright can still penetrate your eyes.

BROWN: That's correct.

MCEDWARDS: This may be a dumb question, I don't know, but I'm wondering if people in the space station can see this or not.

BROWN: It depends on where the space station is actually situated. If they're somewhat behind the Earth, they might be able to kind of look past the limb of the Earth towards the moon and the sun and may be able to see part of that eclipse.

MCEDWARDS: All right, Beth Brown, an astronomer with NASA, thanks very much for your thoughts this morning -- appreciate it.

BROWN: Thank you.

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