This Eclipse is History

A NASA scientist views the event from the foothills of Transylvania, home of ancient legends and modern science.

Aug. 12, 1999: Dracula didn't come out, but the crowds gave a good imitation of how early people reacted when the sun disappeared in the middle of the day. This time the audience knew what was happening and was no less excited.

Right: Video replays of the August 11, 1999 total solar eclipse from NASA TV. Eclipse images were obtained by a team of scientists on a ship in the Black Sea. RealVideo for 56k modems, RealVideo for 28.8k modems, Quicktime. For links to more replays and information about the eclipse see Eclipsecast.com.

"This is sort of like what would happen in ancient times when people would make lots of noise to scare away the demons and dragons that were eating the sun," said Mitzi Adams, a solar scientist at NASA's Marshall Space Flight Center. Adams was in Romania for the last total solar eclipse of the millennium (the next one is in June 2001).

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The event drew viewers to the eclipse's path across Europe - from Cornwall, England, then across the contient from France to Romania - and then into Turkey and western Asia.

"Totality is longest where we'll be observing it," said Mitzi Adams, a solar physicist at NASA's Marshall Space Flight Center noted in an interview last week. Adams worked with an observing team assembled by Dr. Jay Pasachoff of Williams College in Williamstown, Mass. "The centerline almost goes directly through Rimnicu-Vilcea where we'll be based. It's not quite in Transylvania, but I believe you can see the Transylvania Mountains (now called the Carpathian Mountains) from there."

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From their vantage point, they got 2 minutes, 23 seconds of the rarest solar observing time.

In an age of advanced orbital telescopes, eclipses are still valued by scientists because they give the clearest views of the sun's tenuous corona. Although the moon's orbit carries it in between the Earth and Sun every month, conditions are right for a total eclipse only about every 19 months. Then the bright central disk of the sun is blocked out and the corona becomes visible for several seconds to a few minutes, depending on the observer's position along the eclipse path and other factors.

"Pasachoff is a well-known eclipse chaser," Adams explained. But he does it for a reason. "One of the unique things about his expedition is he's bringing a number of undergraduate students who will assist him in his work. He will be making measurements to look for oscillations in the corona."

Educators! Please visit Thursday's Classroom for lesson plans and activities related to the August 11, 1999 total solar eclipse.

Further, Pasachoff's team joined with Dr. Magdalena Stavinschi, director of the Astronomical Institute of the Romanian Academy of Science to take high resolution images of the solar corona. The work also was supported by the coronagraphs aboard the Solar and Heliospheric Observatory (SOHO) which orbits with the Earth. SOHO has a continual view of the sun, but its coronagraphs still cannot see the innermost corona. SOHO's views will complement the images collected by Pasachoff's team.

By a long-distance phone call she described the scene as the moon gradually "ate" the sun.

"People are now making lots of noise, whistling and clapping and in the distance we can hear some drums," she said. Some of the excitement probably was relief that they would get to see the eclipse. The day opened with rain that eventually cleared.

Earlier, as the she noted that people could feel the temperature dropping as less sunlight arrived.

"If it wasn't for my knowledge of eclipses, this would give me pause," she said. "We're getting into the sliver phase [as the moon covers more than half the sun and only a narrowing crescent is left]. Can you hear the crowds?"

The area took on a dim, bluish cast as the sunlight faded and the only light came from the corona and from the sky in surrounding areas where the eclipse was only partial. Parking lot lights came on at a fast food restaurant when it became dark enough to trip photosensors.

Below: An image from the European METEOSAT 7 weather satellite at 1200 UT (high noon in Greenwich, England) shows the eclipse shadow over the Middle East about an hour after passing over Romania (in the upper left quadrant of the picture). Credit: European Organisation for the Exploitation of Meteorological Satellites

"This looks really weird," she continued as her own voice became excited. "You can tell something is going on. We're getting close, we're getting very, very close."

While giving a running commentary, Adams was also taking photographs of the sun to support Pasachoff's studies of the corona.

Finally, at 2:04 local time (11:04 UT), the sun was completely blocked and the crowd could be heard shouting and applauding.

Adams noted that a large prominence - a flame like tongue of hot, dense gas rising through the corona - could be seen on the sun's western limb, and a somewhat smaller one was on the eastern limb. Although prominences and other bright events can be seen with conventional solar telescopes, the solar disk has to be blocked out so scientists can see how the prominences or other features interact with the tenuous corona.

"Oh, it's over already?" Adams exclaimed as the moon continued its march and the sun was again in sliver phase, this time expanding and passing so much light that the corona again is lost in the glare.

The astronomers and eclipse fans (some are both) are now packing their gear for the trip home and to the photolab to get their pictures developed. Then, for the astronomers, the real work begins as they dig through the details of the images they got in 2-1/2 minutes of totality.

Pasachoff reported that "the sky was fabulously clear" and the scientific crew of 12 Williams College faculty and students "had complete and total success" in their observations of the total solar eclipse.

"From our site in Rimnicu Vilcea, Romania," reported Pasachoff in an announcement by Williams College, "we viewed the two and a half minutes of totality in a completely clear sky. We have already played back data from our hard drives, and we can see that we have fabulous scientific data. It should keep my students and me busy for years."

Scientists drawn to midday darkness near Transylvania a pre-eclipse story.

Audio eclipse may fill the sky - August 4, 1999 story on investigations of ionization and radio propagation in Earth's atmosphere during the eclipse

Peering through a Hole in the Sky - June 17, 1999 story on exotic gravity measurements to be carried out during the eclipse

The Millennium's Last Solar Eclipse -- from Sky &Telescope

Solar Eclipse Home Page -- at the NASA/Goddard Space Flight Center

Images of the Earth as seen by METEOSAT 7 at 1200UT during the eclipse.

Pasachoff's eclipse expedition is described at Williams College.

References

Total Eclipses of the Sun, J.B. Zirker, 1995, Princeton University Press

The Sun in Eclipse, Michael Maunder and Patrick Moore, 1998, Springer-Verlag

Totality: Eclipses of the Sun, Mark Littmann, Ken Willcox and Fred Espanek, 1999, Oxford University Press

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