Don York, pioneering astronomer at the University of Chicago, dies at 81
University of Chicago astronomy and astrophysics professor Donald G. York, who is credited with pioneering contributions to the field, died late last month.
York died Friday, Dec. 26 at the age of 81. The university announced his death last week.
As a founding director of the Sloan Digital Sky Survey, York oversaw one of the most significant astronomy projects so far in the 21st century, according to the university.
York was Born in 1944 in Shelbyville, Illinois, along the Kaskaskia River downstate, and moved with his family to Terre Haute, Indiana, after his father died when he himself was 8.
He earned his undergraduate degree from MIT in 1966 and his Ph.D. from the University of Chicago in 1971. As a grad student at the U of C, York worked at the Yerkes Observatory on Geneva Lake in Wisconsin, the university said.
York went on to join a team at Princeton University led by Lyman Spitzer, who is known as a founder of the Hubble Space Telescope, UChicago said. The team was working on the NASA satellite Copernicus, which was launched in August 1972.
York was watching as the satellite detected its first star, as he recalled in a scientific autobiography published in 2024.
In 1982, two years after NASA announced it was planning to shut down Copernicus, York returned to the University of Chicago as a tenured faculty member.
One of York's major interests was exploring the dust and gas that lies between stars and galaxies, known respectively as the interstellar and intergalactic medium, the U of C said. The makeup of interstellar dust was among the subjects of research for which answers had been sought from Copernicus, York wrote.
At the U of C, York mapped the composition of the interstellar clouds of the Milky Way — including the detection of the hydrogen isotope deuterium, which has a neutron in its nucleus in addition to the lone proton of common hydrogen. These discoveries gave scientists the idea that there may be more invisible matter — now called dark matter and dark energy — out in space than visible matter, the U of C said.
York also helped build the Apache Point Observatory in New Mexico. He first oversaw the construction of a multi-purpose telescope at Apache Point, which allowed scientists to attach and swap out instruments easily and to observe remotely from anywhere in the world through a computer network, the U of C said.
Meanwhile, York and several colleagues — including fellow UChicago astronomy and astrophysics professor Rich Kron and Princeton University professor James Gunn — identified a problem and took a revolutionary step toward a solution. The problem was that astronomy was starved for data because of the realities of gaining access to telescopes.
"You could only get about six nights a year for your own personal work on a telescope," York was quoted in a 2022 UChicago News article. "You might find a group to contribute to the data pool for a project and document a small sample, but you were limited by who could work together, how much time people could spend, and how much perfection could be demanded."
Even when a scientist spent time at a telescope and gathered data, the data may or may not have ended up being published, UChicago said. Meanwhile, small groups of scientists worked on different telescopes to obtain similar data, which made it difficult to keep the data reliable, the university said.
This was all both inefficient and insufficient at a time when scientists were looking into questions such as how the present-day universe was influenced by the Big Bang, which required extensive mapping, the university said.
York and his colleagues considered that it would be much easier to explore such questions with "one central telescope that systematically scanned the sky and released calibrated and standardized data publicly, for any scientist to use," UChicago said.
Following a series of meetings at O'Hare International Airport, York and his colleagues hatched the plan for what became the Solan Digital Sky Survey, UChicago said. While there were challenges at first, hundreds of scientists and multiple institutions joined together, and funds were secured to build a second telescope at Apache just for the survey, UChicago said.
York was the founding director of the Sloan Digital Sky Survey, which began taking data in 1998, UChicago said. The survey calibrates and releases data that anyone can download.
The Sloan Digital Sky Survey is now used by astronomers around the world to examine the wonders of the universe — including the presence of a black hole at the center of every massive galaxy, dark-matter halos around galaxies, and dwarf companion galaxies around the Milky Way, UChicago said.
In addition to these textbook-worthy achievements, York was a personable, passionate, hands-on professor. Even if an undergraduate astrophysics course ended up with only one student enrolled as a quirk of changes to the university's Common Core requirements, York would still teach the course to that one student with enthusiasm. The author of this article was in just that position as the lone student in York's course in measuring the expansion of the universe as a UChicago undergrad back in the spring of 2000.
Along with UChicago director of neighborhood relations Duel Richardson, York also cofounded the Chicago Public Schools/University of Chicago Internet Project, bringing the internet to 24 schools on Chicago's South Side. The Hyde Park-based South East Chicago Commission gave York its Community Service Award, and the UChicago Neighborhood Schools Program named its annual award the Don York Faculty Initiative Award, UChicago said.
Among many other journeys, York also traveled extensively to China, for efforts such as convening a conference aimed at 6,000 Chinese high school students on the history of astronomy and organizing a modern cosmology research prize contest for Chinese scientists.
York was the recipient of numerous awards, and published 590 peer-reviewed studies, the U of C said.
He is survived by his wife Anna; children Sean, Maurice, Chandler and Jeremy; and grandchildren Lilia, Anika, Juliet, Samuel, Aeron and Jasper.