Alien civilizations almost certainly wouldn’t be traveling between the stars in ships. In the unlikely event that aliens are in our solar system, it would make

Alien civilizations almost certainly wouldn’t be traveling between the stars in ships. In the unlikely event that aliens are in our solar system, it would make tons more sense to assume they got here via a Bracewell-Von Neumann probe. At which point any “spinning hubcaps” would just be vehicles for exploring the planet and taking samples. (No I don’t believe there are aliens here, but I like my sci-fi to be realistic.)