Lusaka, Zambia — Tourists, journalists and scientists have been arriving in southern Africa to view the total solar eclipse on June 21, 2001. Dr. Jay Pasachoff, an expert on the solar corona, is heading an international observation project, which includes a team of students and faculty from Williams College, who are joined by scientists from five other countries. Among the mysteries the team will explore is that the temperature of the corona is substantially hotter than the temperature of the sun itself.
The extensive preparation for the few minutes that the moon completely covers the sun's face will yield the raw material for weeks and months of analysis. AllAfrica caught up with Pasachoff at his computer in Lusaka, Zambia, 29 hours before the eclipse.
You've observed - how many? - is it your 30th eclipse this year?
My 32nd eclipse.
And does each observation involve more than the last?
Yes, they become more elaborate. We seem to have more equipment - and more people - but it's a lot of fun.
For your last total eclipse observation two years ago, you transported something like 3000 pounds of telescopes, cameras, computers and other equipment. How much did you transport to Zambia?
Well, we fortunately don't have an actual weight! There were quite a lot of boxes that went through the airlines.
And have you added new experiments for this time?
Yes, we've made some modifications, even in the last few weeks, as we get new ideas of things to look at.
In 1991 you did three major experiments: one aimed at learing whether vibrations of magnetic loops generate the extreme temperatures; one mapped those coronal temperatures; and one compared images with those taken from space. Are you looking at similar things this week?
Yes, we're doing those three major experiments, although we have enlarged the goals and apparatus of the second one to include some polarization measurements in conjunction with the scientists from the SOHO spacecraft (Solar and Heliospheric Observatory).
Why do you need to coordinate the imaging on the ground with that from space?
The scientists at the Harvard/Smithsonian Center for Astrophysics who are running the SOHO spacecraft, especially Dr. Peter L. Smith and Dr. John Kohl, are making some polarization measurements of the middle corona. And we are able to make observations on the ground, in collaboration with them, that we hope will calibrate these apparatus, these results, and make all the measurements they make with their telescope more accurate.
Will these experiments move you towards answering the question of why the corona is hotter than the sun that produces it?
We certainly hope so.
Do you lean toward a theory?
Well, we're sure that it's some kind of vibration, or that it's some variation in magnetic field. Whether it's a vibration or a reconnection [of loops of solar gases] from one set of points to another set of points, or another variation in the magnetic field, is what we're trying to find out.
Why do you take so many undergraduates as your researchers - ten, this time?
Because I teach at an undergraduate college and I like them.
Is it primarily a learning experience for them, then, or do they make substantial contributions to the research?
Oh, yes, I wish you were here to see how well they're working, how responsibly they take to working with the apparatus. And of course many of them take to the computers that we use to control the experiment as a fish takes to water.
You make a habit of working with local educators and visiting shools wherever you go to observe eclipses. Why?
I do it because, "A", I'm asked and "B" because the schools need some accurate information, and "C: because it's interesting to do. This afternoon we're supposed to go to a school in one of the local townships, for example, and in my experience the students always have very good questions - and it's good for them to get good answers.
There's been a lot of controversy about whether governments in the path of the eclipse have done enough to educate people about how to protect their eyesight, and even about what precautions need to be taken.
That remains a problem. People are confused by inaccurate warnings, and too many people don't understand that the partial eclipse is very different from totality, and totality is the only part that is very interesting and very dramatic. They mistakenly think that the eclipse glasses that are being widely sold are needed to see the eclipse - whereas for totality, you don't use the glasses as all. People wind up being needlessly scared about science and technology, and the long-term consequences of people not understanding the nature of science and scientific reasoning can be major.
What do you tell the schoolchildren you meet with about how to view the eclipse?
We tell them that if you look at the sun at any time - except when there's a total eclipse - it is too bright to look at safely. So today, or yesterday, or tomorrow, or during the partial phases of an eclipse, part of the everyday sun is visible, and you shouldn't look at it directly unless you're looking through some special solar filter. But during the few minutes of a total eclipse, the everyday sun is covered, and what then comes into view is the solar corona. The solar corona is the same brightness as the full moon and equally safe to look at.
Are you using satellite-gleaned data to help you predict conditions?
Yes we are. If you are talking about what the sun looks like, we are in touch with people at NASA [the US National Aeronautics and Space Administration] and at Lockheed Martin, where two satellites are controlled, and we expect to use that information to decide where we're pointing our telescopes.
So you're constantly connected?
Yes, it's been very important to us to have an Ethernet line and a computer link here.
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People viewing Africa from afar often don't have any conception of African science, especially in a field like astrophysics. What is it like for you and your students to encounter your Zambian colleagues?
Well, the scientists at the physics department at the University of Zambia seem to be good scientists and are well trained. And we had on our second night here a barbecue, which they call a "braai", for our 30 people plus 30 third and fourth-year students from the University of Zambia, and the students had a lot in common. I was interested to hear the courses they are taking, which are very substantial, and similar to what our students are taking. So what they need here is support in the way of equipment. But they are certainly in line with the world training in physics. What we need is support for more people to reach that level here. And we're talking about the capital city. We have not been out in the distant provinces.
One key factor in the success of your experiments - but one over which you have no control - is the weather. Zambia is in the middle of a dry winter, so are the odds in your favor?
The weather has been pretty good the last few days and, well, we're very encouraged. I'm looking out the window at a completely clear sky now. The transparency of the sky is quite good in Lusaka, deep blue, and we just hope for that at eclipse time Thursday.
But, still, don't you toss and turn nervously the night before?
Well, you caught me at my computer here at seven in the morning, and I've been here a couple hours because I just wasn't getting any sleep anyway.
