Ionospheric escape of $${\bf{H}}_{\mathbf{3}}^{\mathbf{+}}$$ H 3 + from Jupiter’s polar regions

Nature Astronomy, Published online: 13 August 2026; doi:10.1038/s41550-026-02950-2 In Jupiter’s polar region, ${{\rm{H}}}_{3}^{+}$ H 3 + has a key role in atmospheric heating and ionospheric conductance. Juno measurements show in situ detection of ${{\rm{H}}}_{3}^{+}$ H 3 + and provide direct evidence of its escape, revealing a pathway for energy transfer between the magnetosphere and the ionosphere.