Wiktionary
preplanetary
a. Before the existence or formation of planets. alt. Before the existence or formation of planets.
Usage examples of "preplanetary".
The system was very busy with vessels going and coming, and mammoth chunks of preplanetary materials being pushed and pulled around by some sort of invisible motivating systems.
Each time he pecked, his fingers were assaulted by the churning voltage, but he kept on until the ship was driving itself into the dirty trail of preplanetary garbage between the gas giant and the star.