New answers tagged vision
Objects do appear larger (or equivalently nearer) underwater when wearing a mask or goggles. See the image below for confirmation of this fact. Why is this? The interface between the water and your mask obeys Snell's law which can be written, in the small angle approximation, as $$ n_1\theta_1=n_2\theta_2. $$ Since air has an index of refraction of ...
Coincidence but it's possible that you had something either outside the house or even inside, moving and possibly with a mirror like surface and what you saw was a reflection. I saw something similar once and resolved the puzzle to a Christmas ornament hanging outside, turning just right at one point to reflect light from the Sun.
I don't know how small these can be made, but a Dove prism is able to rotate images at arbitrary angles
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