We present a combination of techniques to render the aurora borealis in real time on a modern graphics processing unit (GPU). Unlike the general 3D volume rendering problem, an auroral display is emissive and can be factored into a height-dependent energy deposition function, and a 2D electron flux map. We also present a GPU-friendly atmosphere model, which includes an integrable analytic approximation of the atmosphere’s density along a ray. Together, these techniques enable a modern consumer graphics card to realistically render the aurora at 20–80fps, from any point of view either inside or outside the atmosphere.