Images: Related links to external sites (from Bing)Related Studies (from Trip Database) Open in New WindowUltraviolet (UV) rays are an invisible form of radiation. They can pass through your skin and damage your skin cells. Sunburns are a sign of skin damage. Suntans aren't healthy, either. They appear after the sun's rays have already killed some cells and damaged others. UV rays can cause skin damage during any season or at any temperature. They can also cause eye problems, wrinkles, skin spots, and skin cancer. To protect yourselfCheck your skin regularly for changes in the size, shape, color, or feel of birthmarks, moles, and spots. Such changes are a sign of skin cancer. Food and Drug Administration|Definition (NCI)||The exposure to incident light from the sun.|