eli5: Why are the sun rays harmful but not rays for artificial lights?
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What causes sunburns, cancer, some forms of eye damage and a host of other things is mostly UV light, a range of light which operates at a higher frequency than the colors we see. The sun produces A LOT of it. Standard interior lighting produces much less. Artificial lights CAN produce large quantities of UV, that’s how things like those UV sterilizers work, but the commonly used incandescent, fluorescent and LED bulbs don’t.
The sun is hotter and emits rays of a higher frequency. We can’t construct practical lamps that are as hot and last a long time. The power of artificial lighting is also lower. If you turn on a lamp on a sunny day, you can barely see it and can look directly at it without being blinded.
Gas discharge lamps can emit ultraviolet frequencies without using extreme heat. These lamps are harmful to plastics and delicate historical artifacts by making them turn yellow and crack. They can also harm eyes. But their power is much lower than that of the sun, and their harm takes a long time to set in.
There are different kinds of light like red light and green light. There are even kinds of light we can’t see. The harmful light is called UV light. The sun makes UV light as well as others. Our lamp lights don’t produce UV light.
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