For approximately 15 minutes last Sunday morning, people in Williamstown could observe a partial solar eclipse, as the sun rose half covered by the moon. Filters or other viewing apparatuses and a very low and unencumbered view of the eastern horizon were the only requirements to view the eclipse from western Massachusetts. Two hours later, a total solar eclipse swept across Africa, where Jay Pasachoff, professor of astronomy and chair of the International Astronomical Union’s Working Group on Eclipses joined a team of students, colleagues and tourists to observe the natural phenomenon.
“There are total eclipses about every 18 months and annular eclipses (with an annulus, a ring, of everyday Sun remaining visible) also about every 18 months,” Pasachoff said. “A mash-up like this one, beginning annular and then turning total for the rest of the path hasn’t occurred since 2005 … and won’t occur again until 2023.”
In the U.S., the partial eclipse was visible at sunrise, 6:30 a.m. in the Eastern Standard Time zone, after the end of daylight savings time. The silhouette of the moon covered over 50 percent of the Sun’s diameter at sunrise in Boston and New York and 47 percent in Washington, D.C., and Miami. The transient event was only noticeable for about 30 minutes, when the Sun was low on the east-southeast horizon. The eclipse was practically unnoticeable by 7:15 a.m., when the eclipse was about eight degrees high in the sky, comparable to about four fingers at the end of an outstretched arm height. By then, only a tiny bit of the Sun was covered.
The Williams Outing Club provided transportation for around 30 Williams students to see the event from Whitcomb Summit. Unfortunately, they could not see the eclipse through the clouds. “I’m happy I went, but obviously I wish things had turned out differently this morning. The experience has made me want to witness a solar eclipse in the future, though,” Catherine Gerkis ’14, a student in “Stars: From Suns to Black Holes,” said.
Given the time change, the eclipse occured when it was afternoon in West Africa, where the shadow of the moon began in the Atlantic and reached La Lope National Park in Gabon, where Pasachoff and colleagues watched. “We will be alongside the east edge of La Lope National Park,” Pasachoff said before the event. “Gabon is in the midst of transforming itself into a tourist site by putting more than 10 percent of its surface into national parks. We hope to see elephants and gibbons while we are preparing for the observations, and we are hoping that our equipment won’t be trampled by the elephants.” The eclipse then continued across Africa through the Congo, through northern Uganda and northern Kenya, ultimately ending in southern Ethiopia as well as Somalia.
Totality, where the Sun’s light is entirely covered by the moon, appeared in the middle of Gabon for about one minute. This was the longest totality that was visible, but the total eclipse could also be observed for shorter periods of time in other locations across Africa. In Northern Kenya, totality lasted about 10 seconds. Only partial phases of the eclipse were visible in the U.S., in southern Europe and throughout the rest of Gabon and Africa.
Because of the extreme brightness of the Sun’s surface, viewers had to use filters to observe the eclipse safely. Viewers may have created simple “pinhole cameras” by making a small hole, approximately three millimeters wide, through a piece of paper. These “cameras” could then be used to project the Sun onto another piece of paper. With the Sun behind them, viewers could then see the eclipse projected on the second paper. Natural pinholes may also occur from the spaces between the leaves in a tree, so simply looking at the ground under a tree may have revealed crescent images.
For the more dedicated, special filters, almost a million times darker than ordinary sunglasses, could have been utilized. Welder’s glass would have been safe to look through. However, looking for more than a few seconds at a time regardless of filter proves dangerous. Only pinhole cameras, where one looks only at the Sun’s projection, make prolonged staring safe. Pasachoff’s equipment included “a telescope on a mount that tracks the Sun, some of the latest digital cameras including equipment borrowed from Nikon and some special lenses including two borrowed from the National Geographic Society.”
Pasachoff was part of a team of 10, joined by a dozen other people for travel. “Our personnel here includes Allen Davis ’14, Zophia Edwards ’05 (who was previously with me at the 2003 eclipse we saw from a plane over Antarctica) and [Visiting] Professor [of Astronomy] Marek Demianski, who has eight times been a visiting professor at Williams College and who has joined us on several eclipse expeditions.” The group will study their observations from Gabon as well as the observations made from spacecraft from NASA, the Royal Observatory of Belgium and the European Space Agency. Among the team’s goals is to improve scientific knowledge of “space weather”: how particles and light from the Sun interact with the Earth’s atmosphere as well as earth-orbiting communication and other spacecraft.
Pasachoff’s team traveled to Africa with the support of a research grant from the Committee for Research and Exploration of the National Geographic Society. The group is advising and being assisted by the Gabon Space Agency and Nommo Astronomia, the Gabon Astronomy Society, and especially through Dr. Patrice Okouma of the South African Astronomical Observatory.