After a brief tutorial, volunteers look at astronomical images and decide whether the objects they see are galaxies or random noise, a distinction that even the most sophisticated software programs have too much trouble detecting. Volunteers then swipe left or right to indicate whether an image shows a galaxy.
“It’s really exciting to see how enthusiastic the public is about classifying these galaxies,” said Lindsay House, the UT Austin graduate student who leads the project.
The goal is to build the largest 3D map of the cosmos, all focused on galaxies in the early universe to help reveal important clues about dark energy.
The massive research project is designed to reveal whether dark energy changes over time or is constant. At least two-thirds of the universe is believed to be made of dark energy, but scientists know little about it. Understanding how dark energy behaves is a crucial first step toward figuring out exactly what it is, but astronomers need a huge sample of distant galaxies to study to observe dark energy at work. That’s what HETDEX is—a massive survey of more than a million distant galaxies using one of the largest optical telescopes in the world, the 11-meter Hobby-Eberly Telescope at the McDonald Observatory in West Texas.
Dark Energy Explorers volunteers examine images from HETDEX, helping to reduce the time astronomers spend on this task by 90%. That way, the professionals can concentrate their energies on the toughest classifications.
“We’ve tried writing computer code to do this and even used machine learning, but we found the human eye is significantly superior,” Gebhardt said. “We were skeptical at first, but we were blown away by the accuracy.”
To identify the 247,000 galaxies so far, it took volunteers 3.75 million swipes. It takes so many more swipes than galaxies because each candidate galaxy is reviewed by about 15 people to help reach a consensus and increase accuracy.
Dark Energy Explorers was created by a team led by graduate student Lindsay House, HETDEX principal investigator Karl Gebhardt, HETDEX data scientist Erin Mentuch Cooper, professor and astronomy education expert Keely Finkelstein, postdoctoral researcher Chenxu Liu and graduate student Dustin Davis.