ИСТИНА

Galilean moons play significant role in investigation of the Jupiter’s magnetosphere, because their field-aligned projections to the Jovian atmosphere are marked by bright emissions. If the UV emissions in the footprints of Io, Europa, and Ganimede are often seen, the observation of Callisto’s trace is rather hard. One of the reasons is that the ionospheric field-aligned projection of Callisto is located very close to (or even inside) the main auroral oval. The other cause is that Calliso is not always located in the subalfvenic flow of the Jovian magnetospheric plasma. The third circumstance is that the Callisto’s emission occurred to be rather weak. For these reasons, the Callisto’s footprint was observed for the first time only in 2018, using the special technique. The problem of Callisto’s interaction with the Jupiter’s magnetospheric plasma flow is very significant and widely discussed in the literature. Its understanding highlights the key features of the Jupiter’s system.