Sky Mirror is a work of art by Anish Kapoor outside Nottingham Playhouse. It is a polished silver bowl. We'd say that the sky is at infinity as far as the study of Optics is concerned. That's because all the rays of light coming from the sky to the mirror will be parallel. Those hitting the top of the mirror are reflected downwards. Those hitting the bottom of the mirror are reflected upwards. Standing this far away, the rays coming down from the top cross over with the ones going up from the bottom and the picture is upside down. If the mirror is parabolic, there should be a single focal point. If you stand closer than the focal point, the rays don't cross and your reflection is the right way up.
The convex side was harder to see due to building works.
This diagram shows why the image is the right way up, because the rays never cross over.
You see a virtual image - you behind the mirror. If it is the same distance behind as you are in front, the fact that your brain thinks the rays get closer together behind the mirror makes you look smaller.
Of course, you can test all of this with a spoon.
