WILLIAMSTOWN — On a gray, misting Sunday morning in late July, Jay Pasachoff propped open the door to one of the country's oldest observatories, located on the Williams College campus. Shortly after the scheduled arrival of a reporter, he received a few other surprise visitors.

Ranging in age from 3 to 9, Benny and Sasha Gutt and Tula and Theo Brisiel, along with their parents, couldn't curb their curiosity about the hilltop building with stone walls and white staircase spiraling along the exterior like a double helix.

"Come in, come in. Have a look," Pasachoff said, introducing himself as the head of the observatory and the college's astronomy department.

He looked over at the reporter and said: "See what happens when you leave the door open?"

The children and parents, visiting from the New York City area, marveled at the telescopes, the blinking lights of a pulsarium and the antique maps of the night sky.

"I've never met a real astronomer before," said Benny, 6, glancing at the tall, well-groomed, white-haired scientist seated casually before him.

Little did he know that this astronomer happens to be one of the top in the country and in his field.

Observing one of his first solar eclipses at age 16, Pasachoff, who celebrated his 75th birthday July 1, will observe his 69th solar eclipse Saturday, among international colleagues and friends in Sweden. He's gearing up for his 70th — a partial eclipse — slated for Jan. 9, 2019, which he'll view from China or Japan.

Last summer, he and his team made headlines for observing and documenting what was dubbed "The Great American Solar Eclipse," which took place Aug. 21 and left a swath of the world, including the United States, in its path of totality in the dark during the daytime phenomenon. It prompted millions to pause and look toward the heavens.

For scientists, institutional and civilian alike, the event illuminated the sun's corona, offering a rare glimpse into the activity that takes place there, and valuable insight into how the sun's activity can affect the Earth's atmosphere and climate, among other conditions.

Academic or not, it's the kind of science that catches your eye and curiosity.

"I think that it's wonderful that so many nonscientists are interested," Pasachoff said. "Even in Pittsfield, you can look up at night now and see Mars, Jupiter and Saturn bright in the sky."

Saturday's solar eclipse will be a partial one, best viewed from in and around the northern regions of the Arctic Circle, though it will span across northern Europe to Asia. Pasachoff had planned to travel to Kiruna, where the moon will eclipse about 25 percent of Earth's view of the sun from these locations in its path. But rainy weather has kept him in Stockholm, where he expects to see 4 percent coverage, but under ideally sunny skies.

It follows a series of summer eclipses, including a total lunar eclipse July 27 and a partial eclipse that occurred July 13, the latter of which Pasachoff viewed from Tasmania.

"The sky was completely clear. It was just the most gorgeous day," said Pasachoff, who counts partial eclipses as practice runs for events with totality.

The next total solar eclipse will cross the Pacific Ocean next summer, reaching Chile, and Pasachoff plans to be there, too. And in 2024, when the path of totality will pass closer to home — less than 100 miles from Williamstown, in neighboring New York, Vermont and New Hampshire.

With that in mind, Pasachoff said, he has no plans on slowing down or reducing the scope of his work.

"It only gets more and more interesting," he said.

Analyzing data

While astronomical events, like eclipses or this weekend's peak of the Perseids meteor shower, tend to be highlighted in headlines, the most interesting, albeit tedious, work of analyzing observations and data happen more internally within the body of the celestial community.

Several Williams College students who traveled with Pasachoff to study last summer's total solar eclipse at Willamette University in Salem, Ore., have continued to process the data and pursue other related projects this summer. While these students are in their late-teens and early 20s, they're coached to do professional and thorough work, and are respected as scientific colleagues under the tutelage of Pasachoff and other veteran astronomers.

"We took a massive amount of data during our two minutes of totality, and many of us have been working on that data since then," said Christian Lockwood, a rising junior at Williams.

During that expedition, Lockwood captured some stunning imagery, which he used to create a composite image of the event in all its phases. This summer, he is focused on using software to create high-level Python computer programming code that will help the team sort through thousands of eclipse images and "will ensure that better eclipse composites can be made in a shorter time span after an eclipse," he said.

Lockwood also has been working with rising senior Ross Yu and Marcos Penaloza-Murillo, an atmospheric physicist visiting from Venezuela, on analyzing the weather data Yu worked on gathering during totality.

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"We have discovered several very interesting preliminary results in addition to the expected features like a temperature decrease, so stay tuned," Lockwood said.

Another team of students, including rising junior Cielo Perez and rising senior Erin Meadors, are analyzing and classifying other types of data gathered during the eclipse. Perez, in particular, is looking at spectral data, visible through the light streaming around the moon's shadow during the eclipse, to help indicate temperature changes of the sun's corona, its innermost light. Significant changes can indicate how we'll be affected on Earth.

Perez is working to compare data collected by astronomer Aris Voulgaris and his team in Greece.

"I've been working on learning what we should do next with the spectral data," she said. "I've put the images into a small animation that lets us qualitatively see how the intensities of the emission lines changed as the eclipse started and ended."

The students are also working on papers about their respective findings and interests.

Perez said that contributing her part toward the whole advancement of the field of solar astronomy has "helped me better appreciate the papers and textbooks I've read up until this point. Reading a scientific paper only lets one graze the surface of all that it takes to be part of a scientific expedition, generating new and unique data, and then all the work that goes into using that data to get meaningful results."

In addition to their research and leading planetarium shows at Williams, students also had the chance to travel this summer to deepen their knowledge of space and sky.'Amazing experience'

In June, Pasachoff accompanied students to the ZTF Summer Undergraduate Astronomy Institute held at the Zwicky Transient Facility on the California Institute of Technology campus in Pasadena.

"It was an amazing experience, and we learned a lot about the entire field of astronomy. We also were lucky enough to visit several historical and scientific astronomical sites," Lockwood said.

He said those site visits included the massive dome housing the 60-inch telescope at the Mount Wilson Observatory, located just outside Los Angeles, and the Big Bear Solar Observatory, home of the largest optical solar telescope in the world.

"These opportunities cannot be underrated; they are preparing us for a future in our fields," Lockwood said.

In between this, and his own expeditions to this summer's partial eclipses, Pasachoff also has taken part in great meetings of the minds in the astronomical community, keeping the research that his department does in the Berkshires at the forefront of scientists' minds internationally.

This month, he traveled to Genk, Belgium, to present at the Solar Eclipse Conference, typically held in nontotal eclipse years. He'll have a brief respite upon returning from Sweden before he heads to the the International Astronomical Union's General Assembly, from Aug. 20-31, in Vienna. Pasachoff chairs the IAU's Working Group on Solar Eclipses, which is marking its 100th year.

The professor will meet with his colleagues from the U.S., spanning from the East Coast to Hawaii, as well as fellow astronomers from Canada, England, Slovakia, Russia, Japan, China, India and France. Then, he will return to Williamstown just in time for the start of the school year.

This fall, Pasachoff will offer a course on rare books on astronomy, their authors and achievements in the Chapin Library of Rare Books on campus. His colleagues, Marek Demianski, Karen Kwitter and David Tucker-Smith, will teach on topics ranging from the creation of stars to the fate of our galaxy.

As funding for research remains competitive and Earth becomes more sensitive to issues like climate change, Pasachoff and his academic and student colleagues believe that education is key to sustaining their science.

At the upcoming Austria symposium, Pasachoff will discuss the importance of training schoolteachers around the world to become familiar with the foundations of astronomy and to share enthusiasm for the night sky with their students.

"It's important for [astronomers] to be in the room when making [science curriculum] standards," he said.

As a parent and a social studies teacher, Debra Plafker said that's something she can get behind — and it's why her family gravitated toward peeking their heads into the observatory that misty morning in July.

"We are always discovering something new up there," she said, pointing toward the top of the planetarium and beyond.

Perez said guests at planetarium shows bring an endless sense of curiosity with them.

"I find that people are really interested in learning what individual stars or constellations are called, and I can understand why," she said. "There's something really special in being able to look up at the night sky and orient yourself in the universe, even if only by being able to point out and name one or two constellations."

Jenn Smith can be reached at jsmith@berkshireeagle.com and 413-496-6239.