Heyn, in action in Baltimore's Fells Point with that night's feature attraction: Jupiter's moons. Kevin and Sonia McCarthy/Courtesy of Herman Heyn hide caption

itoggle caption Kevin and Sonia McCarthy/Courtesy of Herman Heyn

Shaun Harper of the University of Pennsylvania is a co-author of the new report. Stuart Goldenberg/University of Pennsylvania hide caption

itoggle caption Stuart Goldenberg/University of Pennsylvania