Monster Zero (1965), the 6th Godzilla film: Aliens from Planet X (located between Jupiter and Saturn) try to conquer the Earth using Godzilla, Rodan, and King Ghidorah to take its water supply because water is scarce on their planet.
The Lost Planet (1953) describes journeys to "Hesikos", a fictional asteroid with highly eccentric orbit whose humanoid inhabitants renounced nuclear power after a meltdown, but have meanwhile developed broadcast telepathy.