Lightning was detected on several planets in the solar system, where it is likely to produce sprites or some other form of electric discharge above the thunderstorms in the upper layers of the atmosphere [Yair et al., 2009]. Large sprite discharges at mesospheric altitudes on Earth have been found to be physically similar to streamer discharges in air at sea level density. Based on this understanding, we investigate possible sprite discharges on the Gas Giant planets and on Venus through laboratory experiments on streamers in appropriate CO₂-N₂ and H₂-He mixtures, and variable pressures. Streamer diameters, velocities, radiance and overall morphology are investigated for sprites on Jupiter, Saturn and Venus, by means of fast ICCD camera images [Dubrovin et al., 2010]. We experimentally confirm the scaling laws by examining minimal diameters of streamers. These results are compared to results in air. We observe that streamers in the planetary gas mixtures emit significantly less light in the visible and the near UV range compared to streamers at similar conditions in air. We investigate scaling laws for radiance through calibrated images. The spectra of the discharges are measured; they are dominated by the minority species N₂ on Venus, and by radiative dissociation continuum of H₂ in the gas giants. The spectrum of a fully developed spark is also measured. The spectrum in that kind of hot plasma discharge (similar to lightning) is markedly different from the spectrum created by the cold plasma in the streamers. 

Yair, Y., Y. Takahashi, R. Yaniv, U. Ebert, and Y. Goto (2009), A study of the possibility of sprites in the atmospheres of other planets, J. Geophys. Res., 114, E09002, doi:10.1029/2008JE003311

Dubrovin, D., S. Nijdam, E. M. van Veldhuizen, U. Ebert, Y. Yair, and C. Price (2010), Sprite discharges on Venus and Jupite-like planets: A laboratory investigation, J. Geophys. Res., 115, A00E34, doi:10.1029/2009JA014851.