Astronauts wear gold-plated visors to protect their eyes from intense solar radiation.

The Extravehicular Visor Assembly (EVVA) used by NASA astronauts features a thin layer of 24-karat gold to combat the harsh environment of Low Earth Orbit. Without the Earth's atmosphere to scatter and absorb light, solar radiation is significantly more intense. The gold coating is specifically engineered to reflect infrared radiation, which we perceive as heat, while remaining transparent enough for the astronaut to maintain clear vision.This specialized coating is approximately 0.00005 millimeters (or 50 nanometers) thick, which is roughly 1000 times thinner than a human hair. Despite its extreme thinness, gold is one of the most efficient reflectors of infrared energy in the periodic table. This property prevents the astronaut's face and the interior of the helmet from overheating during direct exposure to the sun, where temperatures can reach 250 degrees Fahrenheit (121 degrees Celsius).The technology was refined during the Apollo missions in the 1960s and 1970s to ensure lunar explorers could work safely on the surface. NASA's Jet Propulsion Laboratory notes that this 'vapor deposition' process is now used in various terrestrial applications, including protecting skyscrapers from heat gain. By blocking 99% of thermal energy, the gold visor acts as a critical thermal shield that allows for several hours of extravehicular activity without the risk of thermal injury or blindness.