The answer, at last! By travelling back to 1947 I found an explanation for mysterious 'flying cutlery', as they used to call it. In Boris Artzybasheff's cartoon you can see Neptunians (yes, that's what they are) firing saucers at Earth. It's not clear where the teapots are going, or why Earth was only deemed worthy of saucers and not the pots.
And talking of flying teapots, perhaps Gong were onto something...
Their album was inspired by Bertrand Russell's cosmic teapot analogy in response to the question of whether a Christian God exists. In his words: 'nobody can prove that there is not between the Earth and Mars a china teapot revolving in an elliptical orbit, but nobody thinks this sufficiently likely to be taken into account in practice. I think the Christian God just as unlikely.'
My first response upon seeing the cartoon was to think of H.R.Giger's work on the Alien film. Had he seen Artzybasheff's cartoon? Were Ridley Scott's aliens firing cutlery through space as part of some cosmic joke? And if one of their stray teapots did get dragged into orbit between Earth and Mars, does that in turn validate the concept of a Christian God? See, you thought Alien was just a great sci-fi film when in fact, buried deep as a sub-sub-text, it's about the existence, or not, of God. And cosmic teapots.