Infrared Radiation When you go outside on a sunny day, you can feel the heat of the sun on your skin. The heat you feel has traveled 150 million kilometers from the sun through space thanks to infrared radiation. Radiation with frequencies below the red end of the spectrum is called infrared. Infrared is different from convection and conduction because it does not require particles to transfer heat. There are no particles in the space between the earth and the sun, but infrared radiation can still pass through it. Every object on earth emits infrared radiation, even cold objects. Infrared cameras can be used to detect it. One of the surprising uses of infrared detectors is rocket tracking. The camera would be connected to an infrared detector, this can not only tell which direction the radiation is coming from, but also how the direction changes. This information is then transmitted to a computer which then processes it and then provides an output that controls the camera and detector to follow the path of the rockets. There are many types of detectors, one of which is the tracer rocket detector, but there is also a detector that has military applications. Living organisms and engines are at higher temperatures than their surroundings and emit more infrared. Special detectors are able to detect the presence of people or engines, even if totally camouflaged, due to infrared radiation, and therefore to discover where an enemy is located. A very similar detector can also be used together with an infrared source to allow seeing in the dark. Infrared radiation is reflected by different objects just like light, but not in the same amount. So a device that can receive this radiation and use it to produce a similar image with light makes the scene visible. This detector has obvious uses, from a military point of view, but it can also be used to observe animals at night, without causing disturbance. An example of the use of infrared for a positive purpose occurs in the Olympic Games of 1972.