The terms shortwave and longwave radiation refer to the wavelength of the radiation, which is the distance from the crest of one wave to the crest of another. The wavelength reflects the energy of the wave. Longwave radiation is less energetic, while shortwave has more energy. Longwave radiation has even longer wavelengths than red light in the visible spectrum, while ultraviolet radiation has wavelengths shorter even than the shortest violet visible light.
Ultraviolet is not the only kind of shortwave radiation; in fact, it is the shortwave radiation closest to visible light on the electromagnetic spectrum. X rays and gamma rays have far shorter wavelengths and thus are more energetic. Infrared radiation is the type of the longwave radiation that is closest to the visible spectrum. Radiation with much longer wavelengths than infrared light include microwaves and radio waves.
The Sun produces its own radiation since it is a body that is much more massive and with a much higher temperature than the Earth. Because of this, the radiation emitted from the Sun is mostly shortwave radiation. The Earth emits radiation as well, but it is infrared radiation emitted in the form of heat that is not visible to human eyes.
