Question: how does sun reflect of surfaces that arent mirrors

Alistair Glasse answered on 13 May 2025: last edited 13 May 2025 10:59

Everything reflects or scatters sunlight, but some surfaces reflect more than others. Light is an electrical vibration. When it hits an object it can make the electrons in the object start vibrating, if they are free to move. Vibrating electrons can then generate ‘new’ light vibrations – that’s the relfection. So.. materials where the electrons can move easily reflect (re-emit) a lot of the light falling on them. Other materials where the electrons can’t move so easily dont reflect light so well. (Radio waves are also light, which is why wifi aerials are made of metal; the radio ‘light’ makes electrons in the aerial vibrate to make an electrical current.
The amount of light an object reflects is also affected by its surface structure – if its got lots of holes and craters the light bounces around until it runs out of energy. That’s why polished mirrors reflect more than dirty mirrors.