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Electrically conducting fluids can generate a magnetic dynamo when layers of fluid slide past one another, often at different rates. Known as shear, this is how the Earth and the Sun produce magnetic fields. But exactly how large-scale spatial coherence over the entire surface of the Sun can arise at high magnetic Reynolds numbers, as lines of magnetic field are dragged along by fluid flow, has remained unclear. For such turbulent flow, the magnetic field tends to have small-scale structure. Steven M. Tobias and Fausto Cattaneo report simulations that show how the observed organization is possible. In their approach, the authors use the shear to suppress the growth of fluctuations at small scales, thus allowing the large-scale structure to flourish. When the fluid velocity has a strong helical component, they find two bands of magnetic structures with large-scale organization, which they identify as Parker dynamo waves — propagating hydromagnetic waves that were first predicted in 1955. It remains to apply this mechanism to a solar model, although it is appropriate for any astrophysical dynamo. MC