Eclipse expedition reports 'fabulous results' from Romanian site

August 11, 1999

WILLIAMSTOWN, Mass., August 11, 1999--Williams College astronomer Jay M. Pasachoff reported today that "the sky was fabulously clear" over Rimnicu-Vilcea, Romania, and the scientific crew of twelve 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, "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.

An unusual aspect of Pasachoff's experimental teams is that they include so many undergraduate students, including Williams College students Kevin Russell of Lyon, France, Sara Kate May of Littleton, N. H., Rebecca Cover of Sharon, Mass., Daniel Seaton of Wayne, Penn., Joey Shapiro of Langley, Wash., Misa Cowee of Albany, Calif., Darik Velez of Hanover, N.H., and Rossen Djagalov of Stara Zagora, Bulgaria; Keck Northeast Astronomy Consortium Summer Fellow Alexandru Ene, a student from Romania who studied at Middlebury College, and Mark Kirby, from Deep Springs College in Dyer, Nevada. Recent Williams alumni Timothy McConnochie '98 and Christina Reynolds '97 are also on site.

"We have had a dozen Williams students as well as faculty and staff on site in Romania for the last two weeks. They have set up and aligned some ton and a half of equipment. It all paid off with today's magnificent results."

"We are studying the outer part of the sun, the corona," said Pasachoff. "The corona expands to envelop the Earth, so by studying it we are studying our environment in space. This year and the next two are especially active times for sunspots and other tracers of the sun's magnetic field, so the corona was not only especially interesting but also especially beautiful this time. Bright streamers bristled from the Sun in all directions and red prominences gleamed out at the Sun's edge.

"Our experiments were meant to study how the corona gets so hot, how its temperature changes from point to point, and how the magnetic field shapes it."

The research team from Williams College, Williamstown, Massachusetts, headed by Pasachoff, is studying a number of aspects of the solar corona.

Two of the three experiments deal with the still open question of how the corona, the outermost layer of the sun's atmosphere, can reach a temperature of two million degrees Celsius (about four million degrees Fahrenheit), even though the everyday surface of the sun below it is only 6,000 degrees Celsius (about 11,000 degrees Fahrenheit).

The third experiment is in liaison with scientists in charge of an experiment on the Solar and Heliospheric Observatory (SOHO) spacecraft. The experiments are in collaboration with Dr. Bryce Babcock, staff physicist at Williams College.

The observations are possible only during the brief minutes of a total solar eclipse, when the everyday sun is hidden by the moon, allowing the faint corona to be observable from earth. On ordinary days, the corona is hidden by the blue sky, since it is about a million times fainter than the layer of the sun we see shining every day, the photosphere.

Pasachoff, together with Dr. Leon Golub of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, is coauthor of the first textbook about the solar corona to be written in decades; it was published in 1997.

Description of the experiments

The first experiment is a search for rapid oscillations in the corona, with periods of about one second. Pasachoff and his colleagues have developed techniques over the last two decades to observe in the so-called "coronal green line," a color in which the corona emits light especially strongly, with time resolution so fast that such short periods can be detected. Oscillations with periods in that short range are predicted by some theories that hold that the extreme coronal heating is caused by vibrations of magnetic loops. The loops of gas, held in place by the sun's magnetic field, have been observed, and the question is whether their vibrations bring enough energy into the corona to heat it sufficiently. The experiment is supported by a grant from the Atmospheric Sciences Division of the National Science Foundation.

The second experiment is a map of the temperature of the corona, using a technique of comparing electronic images of the corona taken at special ultraviolet wavelengths. Following theoretical work, these wavelengths are chosen to include two such at which the difference between the shape of the everyday sun's spectrum and the corona's spectrum is especially striking. The experiment is supported by grants from the Committee for Research and Exploration of the National Geographic Society.

The third experiment is to image the solar corona during the eclipse to compare with observations of the corona seen with the Extreme-ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO), in collaboration with scientists at NASA's Goddard Space Flight Center. The features seen at the eclipse outside the solar disk will be matched up with their bases seen on the disk with the EIT experiment. The experiment is funded by a grant from NASA's Guest Investigator Program for the SOHO spacecraft.

More about the expedition

Dr. Allan Ridgeley of the Rutherford Appleton Laboratory, England; Prof. Marek Demianski of the Copernicus Astronomical Center in Warsaw; Mitzi Adams of the NASA Marshall Space Flight Center, and Paul Rosenthal are with the group in Romania. Bryce Babcock and Stephan Martin of Williams College, Lee Hawkins of Wellesley College and Appalachian State University, Jonathan Kern of Caltech, and Paul Rosenthal of Williamstown comprise the staff."

Student participation in the expedition is funded by the NSF, National Geographic, and NASA grants; by the Keck Northeast Astronomy Consortium; by the Massachusetts Space Grant, which is funded by NASA; and by the Safford Fund and the Brandi Fund at Williams College. A collaboration among Williams College, the Rutherford Appleton Laboratory, and the Astronomical Institute of the Romanian Academy of Sciences is funded by NATO. The expedition is supported by grants from NASA's Guest Investigator Program for the Solar and Heliospheric Observatory spacecraft, from the Committee for Research and Exploration of the National Geographic Society, and from the Atmospheric Sciences Division of the National Science Foundation.

Pasachoff is Field Memorial Professor of Astronomy, chair of the Astronomy Department, and director of the Hopkins Observatory at Williams College. He is also chair of the Working Group on Eclipses of the International Astronomical Union. He is the author of the Peterson Field Guide to the Stars and Planets in addition to astronomy texts.

Scientific staff also includes Dr. Bryce Babcock of Williams College; Lee Hawkins of Wellesley College; Stephan Martin of Williams College; and Jonathan Kern, Optics Scientist at the Laser Interferometer Gravitational-Wave Observatory of Caltech.
For more information,, and, for specific Williams expedition information and

During July 29-August 12, the expedition will be at the Alutus Hotel, Rimnicu-Vilcea, Romania. phone from US: 40-50-736601; fax from US: 40-50-737760

Founded in 1793, Williams College is the second oldest institution of higher learning in Massachusetts. It is consistently ranked first in academic reputation among all liberal arts colleges. The college of 2,000 students is located in Williamstown, which has been called the best college town in America. You can visit the college in cyberspace at

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