Today I was sitting at my desk where I volunteer and it was kind of slow so I started messing with my desk lamp. I wondered how fast light travels from the bulb to the desk surface, but I didn't know. What I want to know is about how fast does the light travel to hit the desk when the light bulb from the lamp is about 12 inches above the desk? How fast does it take for my eyes to see that light? And there was even a sort of small rainbow in the circumference of the light, where light meets shadow, why is that? Also, I blocked the bulb with my hand and I would seperate and close my fingers really fast a couple of times (well I guess not that fast, but as quick as I could), how fast does light take to reach the desk then? I know these are weird questions but I'm curious to know!