Fire and water mix at sunset over Tucson; some scientists speculate that lightning is more likely to occur in areas of heavy rainfall. Lightning does occur without rain, however. It might even happen extraterrestrially. In 1979 the Voyager 1 spacecraft relayed images of what may be lightning in Jupiter's atmosphere. Scientists studying Venus are also seeking evidence of lightning. Since there is very little water in the Venusian atmosphere, lightning would provide convincing evidence of active volcanoes on the planet, a cosmic question that could be solved in a flash.