I think your priors on "optical illusions" are unreasonably low. I too once saw a seemingly inertia-less gleaming silvery orb streaking across the clear blue sk

I think your priors on "optical illusions" are unreasonably low. I too once saw a seemingly inertia-less gleaming silvery orb streaking across the clear blue sky. If it had flown away just a moment sooner, I might never have realized that it was in fact a fluffy seed pod, some 15 yards away.