Relative humidity. Relative humidity (RH) is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. Relative humidity depends on temperature and the pressure of the system of interest. It requires less water vapor to attain high relative humidity at low temperatures; more water vapour is required to attain high relative humidity in warm or hot air.
silver is the color of the element mercury silver is the color of the element mercury Silvery.
I've seen the same planet colored differently in different photos. Here are the true colors of the planets, with links to some relevant images from NASA spacecraft. (Note that spacecraft photos appearing in the media often have false coloration.) Mercury: gray (or slightly brownish). Mercury has practically no atmosphere, so we just see the rocky surface.