On a frigid orbit beyond Neptune, some of the solar system’s smallest worlds project a strange silhouette. Two rounded lobes, pressed together with a narrow “neck,” like a snowman that never melted. Those shapes are common enough to demand an explanation. In the Kuiper Belt, about 10 percent of planetesimals are “contact binaries,” two bodies that touch and stay touching. NASA’s New Horizons made the form famous in January 2019 when it flew past the Kuiper Belt object (486958) Arrokoth, a bilobate world with a smaller lobe called Wenu and a larger one called Weeyo. A new set of simulations led by Michigan State University graduate student Jackson Barnes argues that the snowman look can emerge from a basic process: gravitational collapse. The work is published in Monthly Notices of the Royal Astronomical Society. A common shape needs a common origin Scientists have floated plenty of ideas for how contact binaries form, including later-life events that push two once-separated partners together. Some proposals involve gas drag, Kozai–Lidov oscillations, or combinations of effects that change a …