A week after finishing her dissertation on the formation of the moon, Robin Canup danced the lead in Coppelia with the Boulder Ballet. “At the time, it felt like I had a wonderfully full and busy life,” she says, “but I can’t believe now I did it all.” Canup, 35, stopped dancing professionally five years ago. “By that age you’re an old dancer but a young scientist,” she says. Still, there’s an unexpected harmony to her career: Now she studies how moons glide around planets in space.