What are some sources of infrared?
The sun is definitely a source of infrared (as it emits radiation from across the electromagnetic spectrum). As far as I can see, the aeroplane, radio and antennae would not be sources of infrared. The radio does not emit anything, it is just a receiver. Aeroplanes and antennae are sources of radio waves which is on the electromagnetic spectrum but separate to infrared (remember infrared is a form of light). The only other common things I can think of that are sources are remote controls (which use infrared light to transmit the information to a TV or whatever).
