Good science requires good data. But in many cases, the data depends on the identification of thousands of objects in images, from microscopic organisms to distant galaxies.
Even three decades ago, this torrent of data bordered on unmanageable.
But not for Lucy Fortson, a University of Minnesota astrophysics professor in the College of Science and Engineering’s School of Physics and Astronomy. In 2007 she co-founded Zooniverse, a platform for volunteers to classify images online. So far, classifications have come from more than three million citizen scientists worldwide, including more than 100,000 from Minnesota.
On June 29, 2026, Fortson and other Zooniverse enthusiasts welcomed the long-awaited arrival of the billionth image classification.
“What this one billion milestone means to me is, it validates the idea that we can do research in which we engage the public as a true partner,” Fortson says. “As a co-founder of Zooniverse, I find this immensely gratifying.
“And I want to thank all our volunteers.”
In 2023 the White House Office of Science and Technology Policy named Zooniverse a Champion of Open Science.
Citizen scientists at work
On Zooniverse, anyone can examine images from research projects in a range of fields, from astronomy to medicine to wildlife science. After a brief training, volunteers view images and are asked to classify them as, to give some examples, “galaxy” vs. “not a galaxy,” or “a zebra in motion” vs. “not a zebra in motion.”
“Galaxy Zoo was the first Zooniverse project, in 2007,” says Hayley Roberts, a postdoctoral researcher in the School of Physics and Astronomy. “Lucy and astrophysicist Chris Linott, at Oxford University [England], got it started.”
In 2007 Galaxy Zoo volunteers found a new class of galaxies, called “Green Peas” due to their small size and color. As projects and topics multiplied, the platform’s name changed from Galaxy Zoo to Zooniverse.
Another University of Minnesota-related Zooniverse project is the long-running Snapshot Serengeti, started and headed by Craig Packer. For Packer, a professor in the College of Biological Sciences and a leading expert on African lions, the images have been a gold mine of data on the ecology of lions, which face threats that include heavy trophy hunting.
"The camera grid really helped us learn more about how lions coexisted with their prey and with other predators," Packer says. 'It also helped us solve the riddle of the grazing succession of zebra, wildebeest and gazelle during the great migration of the Serengeti."
Working with astronomical numbers
Roberts and fellow postdoc Tom Donlon study the many ways galaxies like the Milky Way form and merge, often in repeated encounters, taking advantage of the millions of images available.
In work like this, a researcher may submit to Zooniverse a project to identify galaxies that are spiral — that is, flat rather than football-shaped and with curved, star-rich “arms” that give them a pinwheel appearance. Examples include the Milky Way and Andromeda, our closest large galactic neighbor. After being trained on how to spot spiral galaxies, volunteers are shown a series of galaxy images to classify as either spiral or not spiral.
For some galaxies, the structures will be clear and all the volunteers will agree on how to classify them. But other galaxies will be fainter, sometimes even hard to distinguish from the background.
Typically in such cases, says Donlon, if at least 80 percent of volunteers classify the galaxies as “spiral,” that verdict will be accepted. If there’s a lot of disagreement, researchers will ask for more viewers to be shown the image.
With enough images classified, researchers like Roberts and Donlon will have a better idea of how various galaxies look from different angles, how they interact with neighboring galaxies, and how they contribute to the evolution of the universe.
Zooniverse volunteers also work on written material. "Because machines find cursive hard to read, we use Zooniverse volunteers to transcribe handwritten documents, and those transcriptions are used to train an AI model," Fortson says.
A continuing collaboration
Collaboration and connection with the public is a widely shared trait among University researchers. James Kakalios, head of the School of Physics and Astronomy, places the one billionth Zooniverse classification squarely into that context.
“The School of Physics and Astronomy has a well-deserved reputation for outreach and engagement efforts,” he says. “Starting with Physics Force more than 40 years ago, the School has been an active partner with the public in Minnesota and around the world. Zooniverse has been a star in the effort.
“This milestone shows that science is truly for everyone, and everyone can do science.”
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