According to the Encyclopaedia Britannica, solar radiation is electromagnetic radiation, including infrared and ultraviolet light, radio wavelengths, X-rays and the visible spectrum. The Sun's attendant planets and their satellites receive about 1 part in 120 million of the massive solar radiation the Sun emanates each second.
Sunlight is the visible spectrum of electromagnetic radiation seen by humans. This visible light and the other wavelengths of solar energy intercepted by the planet is essential to life on Earth and to the natural processes that take place on its surface. The Sun radiates about 8 kilowatts of power per square centimeter on its own surface.