Triton is shown to be the dominant source of plasma for L ≳ 7 in the magnetosphere of Neptune. Triton maintains neutral hydrogen torus of average density comparable to or greater than that of the Titan torus at Saturn. The Triton torus may be detectable in H Lyman-α emissions. However, the energy source from plasma outward transport and mass loading in the Triton torus is insufficient to explain the Neptune aurora. It is proposed that Neptune's aurora is driven mainly by a solar wind interaction.