The sun emits several types of radiation, and much of it reaches the earth's surface. In the above animation, the energy of the radiation increases from right to left. Warmth from the sun is due to infrared radiation, while the light and colors we perceive are due to visible radiation. Neither infrared nor visible radiation is harmful under ordinary circumstances. Moving toward the high energy part of the spectrum is ultraviolet radiation, a known carcinogen (cancer-causing agent). Both UVA and UVB radiation reach the earth's surface. Exposure to either increases your risk of melanoma and other skin cancers. UVC radiation and X-rays have even higher energies, but are absorbed by the atmosphere and never reach the earth's surface.