Radiation usually has negative connotations, associated with treatment given to cancer patients. It is also considered to be something that cannot be seen with the naked eye. When people are asked to give examples of radiation, light is normally not considered. However, visible light also forms part of the electromagnetic spectrum.

Stars emit different types of radiation, including light. What about infrared and ultraviolet radiation? Infrared radiation is usually associated with heat. Some objects are so hot they also emit visible light, such as fire. However, as humans, we are not as hot and only emit infrared waves. Our eyes are not so sensitive to infrared waves, but night-vision goggles or infrared cameras are able to pick up the signals emitted from warm objects, such as humans and animals. Ultraviolet light (UV) is also invisible to the human eye although some insects are able to see it. Visible light is only a small part of the electromagnetic spectrum.