Nice. I see I will have to visit you again on NFD.the main engines of my titan.
Sounds more like a bug, that happen to me with a ship instead of a planet a while ago.Last night I started a new single player universe. I looked at the map in the spawn system and noticed an ice planet right beside a green planet. I thought that might be cool so I went and took a look. There was nothing special about the green planet. The ice planet on the other hand was untargettable, unlike most planets. As I was heading towards it, I couldn't see the usual planet plate indicators like I saw on the green planet. As I got closer, I noticed the surface had no depth or terrain blocks on it. It was then obvious to be a planet core with an icy texture on it. I thought I would try landing on it so naturally I slowed down my ship. The distance between my ship and the planet was increasing. I stopped my ship, ...the planet was moving away from me!
So unless this is somehow a bug, I think I just discovered a secretly implemented mechanic for orbiting moons. More exploration is necessary.