In a laboratory simulating conditions on Jupiter's moon Europa at NASA's Jet Propulsion Laboratory in Pasadena, California, plain white table salt (sodium chloride) turned yellow (visible in a small well at the center of this photograph). The color is significant because scientists can now deduce that the yellow color previously observed on portions of the surface of Europa is actually sodium chloride. The JPL lab experiments matched temperature, pressure and electron radiation conditions at Europa's surface. https://photojournal.jpl.nasa.gov/catalog/PIA23273