Is there a difference between:stars,filament bulbs,animals that produce light?
An incandescent light bulb is in some ways very like the sun, although not nearly at the same temperature: they are both what we call “Black-body radiators,” which radiate light because they are very hot. There are, of course, major differences: the sun is more like a static sphere of lightning than like a superhot metal filament; it’s a ball of hydrogen and helium plasma. But it’s still black-body radiation. (You might wonder why we call these things black-bodies. It’s because we physicists measure color in a peculiar way: if we shine a light on something, how does our visual perception change? It turns out that if we shine a light on the sun, it will perfectly absorb the light we shine on it, and not reflect any of it back — making it “black.”) As opposed to incandescence, animal light is generally luminescence. The biggest distinction here is temperature: an animal just cannot hold its bum at a thousand degrees Celsius; that would burn the animal. The light is instead generated by
