The phrase "parent planet" refers to a planet from which other planets or moons are formed. It is like a parent giving birth to its children. Full definition
But unlike divorcing couples, if you're happily married yet come from different parenting planets, no court order is going to usher you into counseling or parenting classes. (nansilver.net)
The parent planet no longer exists, though — it was smashed to smithereens in the solar system's violent infancy. (sciencenews.org)
«Like good children, our moon and most others keep one face focused attentively on their parent planet,» said Douglas Hamilton, professor of astronomy at the University of Maryland and a co-author of the Nature study. (sciencedaily.com)