Electrons in a magnetic field undergo cyclotron motion at a particular frequency – cyclotron frequency. Whistler waves are a type of natural plasma waves with frequencies below the electron cyclotron frequency. These waves occur in the Earth’s ionosphere and magnetosphere, sometimes in association with atmospheric lightning. In the magnetosphere of Jupiter, they are believed to play an important role in both the acceleration of electrons to high energies and the loss of these energetic electrons.
Li et al.  have recently produced the first global maps of such whistler mode waves in the Jovian inner magnetosphere, by combining the new data from the NASA Juno spacecraft with some historical data from the Galileo spacecraft. These global maps reveal for the first time the very large latitudinal extent of whistler waves and signal their important roles in the radiation belts on Jupiter.
Citation: Li, W., Shen, X.‐C., Menietti, J. D., Ma, Q., Zhang, X.‐J., Kurth, W. S., & Hospodarsky, G. B. . Global distribution of whistler mode waves in Jovian inner magnetosphere. Geophysical Research Letters, 47, e2020GL088198. https://doi.org/10.1029/2020GL088198
—Andrew Yau, Editor, Geophysical Research Letters