by Cyril Simon Wedlund, BIRA-IASB, Brussels, Belgium

South auroral oval and polar rain simulated in laboratory using the Planeterrella experiment (J. Lilensten et al., UJF/CNRS, Grenoble, France).
The Planeterrella was redesigned after K. Birkeland's original terrella experiments, which in the 1900s helped him unveil the mechanisms at the origin of polar aurorae.
A magnetised aluminium sphere is placed in a vacuum chamber. An electric current is then established between the sphere (anode) and the electrode at the top of the figure (cathode) producing emissions in the visible and UV ranges.

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