Driver's vision enhancer and DRS Technologies. All objects above Absolute zero (−273.15 °C / −459.67 °F) emit infrared radiation (IR), an invisible form of light beyond the optical spectrum. The optical spectrum is part of the electromagnetic energy spectrum which consists of ultraviolet, visible, and near, middle, and far-infrared energy. Only a small part of the optical spectrum is visible to the unaided eye. The Sun emits energy across the entire electromagnetic spectrum. Solar energy strikes the surface of objects. Some of that energy is absorbed and stored as heat (thermal energy). After sunset, this thermal energy remains and is emitted in the
Ultraviolet communication in butterflies to reflect ultraviolet light. In effect, females are removing the ultraviolet signal that initiates male sexual behavior, resulting in the abrupt halt of male sexual behavior. Female White Cabbage Butterflies take advantage of the personal butterfly ultraviolet communication system to also reject males by removing an ultraviolet reflectance signal. Some butterfly species use ultraviolet light as a method of signaling their sex. For example, in the species "Eurema lisa", males possess the structural requirements necessary to reflect ultraviolet light discussed previously, but females lack the ultraviolet light reflecting ridges. In both sexes of this species, a flutter response, or the