I bet you’ve never seen water do this: twist and turn like a dancer in flight. It happens when a droplet lands on a water-repellent surface with a special pattern. These acrobatic leaps were recorded by Chinese scientists investigating new ways to manipulate water. To understand what they did, let’s step back and see what Isaac Newton had to say about bouncing objects. According to Newton, when an object hits a solid surface, some of the energy of the impact is translated into a rebound. Think of a ball hitting concrete. If the ball travels straight down with no spin, it should bounce straight up again. And it’s the same with a water droplet on a water-repellent surface. Theoretically, the droplet should bounce straight up — no fancy stuff. But the researchers created a pattern of adhesive material on the surface that water sticks to. The water in contact with the sticky patches recoils more slowly than the water touching the repellent surface, and that makes the droplets spin. Change the pattern of the adhesive, and you change the shape of the dancing droplet. The researchers made swirls and half-moons and dotted circles, each of which caused the water to behave differently, sometimes even bouncing sideways. Scientists also showed how the energy of the droplets could be harvested. They set up a magnetically suspended surface. As the droplet landed on the surface and rebounded, it pushed down the plate and caused it to spin. It’s a new kind of hydropower. And at their peak, those droplets are spinning at a whopping 7,300 revolutions per minute. So apart from creating a water droplet ballet, scientists have also found a new way to harvest energy. And their work might help in designing self-cleaning airplane wings. For now, it’s enough to have the pleasure of watching the leaps and pirouettes of those dancing drops.