optics

Water is, as far as I know, a very pale blue. So why do clouds, consisting of fine water drops, appear white? Is it that water only filters out the blue fraction of light passing through, but affects reflected light differently, or are clouds actually blue, but the much deeper blue of the...

If an astronaut, equipped with a flashlight, was floating inside a sphere with a perfectly reflective surface, what would he see? Is there any software which could render his view approximately, or can it be figured out just with pen and paper?

MacDonalds Spiderwick Chronicles Toy given away with happy meals in the UK consists of a "lens" and an LED. When you hold the lens up to your eye and look at the lit LED about a foot away you get a grid of repeated small images. Anybody know how this effect works or what it is called? The...

I was wondering if anyone here had an opinion one way or the other on the theory that painters in the 15th century used lenses and mirrors to assist them with drawing and painting some of their works. It supposedly worked similar to a camera obscura, but in this case a lense or mirror is used...