What is the correct possessive adjective for...

Venereal is appropriate, if you’re wanting to describe something that is a human characteristic. If, on the other hand, you’re trying to describe something that refers to the planet Venus, you must say Venerian, as in, “The surface of the Moon is not at all Venerian.” You can also say Venusian or Cytherean in that context. Here’s a helpful list of the other planets and their possessive adjectives: Mercury-Mercurian or mercurial; Earth-Terrestrial or Telluric; Mars-Martian, Arean, or martial; Jupiter-Jovian or jovial; Saturn-Saturnian or saturnine; Uranus-Uranian; Neptune-Neptunian; Pluto-Plutonian.