A Whistler is a low frequency radio wave generated by lightning. [1] (http://www.loscrittoio.it/Pages/MM-0700.html). In addition to Earth they have been received from Jupiter showing the presence of lightning there.
Whistlers and Related Ionospheric Phenomena, Robert A. Helliwell, Stanford University Press, Stanford, California, 1965. See also Whistlers and VLF Emissions by the same author. (These are best sought in a library)