Final answer:
Solar energy reaching Earth is primarily in the form of electromagnetic radiation, including visible light, infrared, and a small amount of ultraviolet radiation.
Step-by-step explanation:
When solar energy reaches Earth, it is primarily in the form of electromagnetic radiation. The sun emits a wide range of electromagnetic waves, including visible light, infrared, and a small amount of ultraviolet radiation. However, only a fraction of this energy is visible to the human eye, which we refer to as 'visible light.' The energy of a wave can be measured by its wavelength, which is the distance between two consecutive, similar points of the wave. Shorter wavelengths, such as gamma rays and X-rays, carry more energy than longer wavelengths, like radio waves.