Thus, the viewer of a false color image must always be told by the creator of the image what the colors mean. Many of the characteristics of an object in interstellar space depends upon the form that hydrogen is in. Infrared light is another part of the electromagnetic spectrum and lies beyond what humans can see as red light. Infrared light can be produced by objects with temperatures from about zero to 2000 degrees Fahrenheit. In fact, our bodies produce infrared light that can be observed using special devices.
Some nocturnal animals have eyes that can see the infrared light produced by their prey or enemies.
Ions are atoms whose electrons have been stripped from them because of the high temperature. Interstellar gas occupies the space between stars. It is a very thin gas with, on the average, one atom in a volume the size of your thumb. The interstellar medium is is made up of interstellar gas and dust. The gas comes in patches that astronomers call interstellar clouds.