Heat is energy in transit that flows due to temperature difference. Unlike heat transmitted by thermal conduction or thermal convection, thermal radiation can propagate through a vacuum. Thermal radiation is characterized by a particular spectrum of many wavelengths that is associated with emission from an object, due to the vibration of its molecules at a given temperature. Thermal radiation can be emitted from objects at any wavelength, and at very high temperatures such radiations are associated with spectra far above the <answer>infrared</answer>, extending into visible, ultraviolet, and even X-ray regions (i.e., the solar corona). Thus, the popular association of <answer>infrared</answer> radiation with thermal radiation is only a coincidence based on typical (comparatively low) temperatures often found near the surface of planet Earth.
The visible, ultraviolet and X-ray spectra are all above what spectrum?
infrared