Anyone with a magnifying glass or a shaving mirror can light a fire by focussing sunlight into a spot on a piece of paper and burn a hole.

Can the same trick be done with starlight? If so what diameter of mirror or lens will be needed? And which star would be the best choice?

What colour would mirrors be classified as?

If you look into the corner of the intersection between two mirrors at right angles, at 60 degrees, 45 degrees etc you get a series of confusingly-behaved reflections. Think about them and explain.

If you have a bit of cash and suitable tools, explore and explain what you see if you let three mirrors meet at a corner, in particular, two can be normal rectangular mirrirs, but you can do a bit of geometry and cut triangles at various angles to make corner cubes, sixty-degree-corners and so on. (Trickier than it sounds!)

But now, something that I would love to see would be cones of good glass or optical grades of plastic that one could look into from below. I have ideas about what they would show, but has anyone seen such things in real life?

Or is there a good bit of ray-tracing freeware that would help?

If I make a box out of mirrors, then open the box in order to to let light in, then I close the box. Why does light not stay stored in the box?

I'm short-sighted, and during a recent haircut realised that objects far behind me still looked blurry in the mirror. If the light is reflecting from the mirror (which wasn't far away), why is it blurry?

My 9 yr old son asked me: if he installed a torch inside a sealed flask made of mirrors and illuminated it briefly, would the light remain in the flask to "flash" out if it were opened. I answered that the light would decay away as mirrors do not reflect all the light and that this would be to quick to measure the decay period - thus, when opened, there would be no light relecting around in the flask. Am I right?