 Infrared, Infrared radiation IR is electromagnetic radiation EMR with longer wave lengths than those of visible light, and is therefore generally invisible to the human eye although IR at wave lengths up to 1050 Nm from specially pulsed lasers can be seen by humans under certain conditions. It is sometimes called Infrared light. IR wave lengths extend from the nominal red edge of the visible spectrum at 700 Nm frequency 430 ThZ to 1mm 300 GHz. Most of the thermal radiation emitted by objects near room temperature is Infrared. Like all EMR, IR carries radiant energy and behaves both like a wave and like its quantum particle, the photon. Infrared was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. Slightly more than half of the total energy from the sun was eventually found to arrive on Earth in the form of Infrared. The balance between absorbed and emitted infrared radiation has a critical effect on Earth's climate. Infrared radiation is emitted or absorbed by molecules then they change their rotational vibrational movements. It excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared range. Infrared radiation is used in industrial, scientific, military, law enforcement, and medical applications. Night vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected. Infrared astronomy uses sensor-equipped telescopes to penetrate dust origins of space such as molecular clouds, detect objects such as planets, and to view highly red-shifted objects from the early days of the universe. Infrared thermal imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatus. Active uses for military and civilian applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wave lengths around 10 meter micrometers. Non-military uses include thermal efficiency analysis, environmental monitoring, industrial facility inspections, detection of grow ops, remote temperature sensing, short-range wireless communication, spectroscopy, and weather forecasting.