Rosetta spies unexpected ultraviolet aurora at comet
ESA's Rosetta mission has revealed a unique kind of aurora, an exciting phenomenon seen throughout the Solar System, at its target comet, Comet 67P/Churyumov-Gerasimenko. This image shows the key stages of the mechanism by which this aurora is produced: as electrons stream out into space from the Sun and approach the comet, they are accelerated and go on to break down molecules in the comet's environment. This destructive process can throw out excited atoms, which then 'de-excite' to produce the observed aurora. To reveal the auroral nature of the emissions, the study relies on a set of in situ and remote-sensing instruments aboard Rosetta (RPC, ROSINA, VIRTIS, MIRO and Alice), as shown to the right of the infographic in the spacecraft schematic.