The Webb Telescope's mirrors are coated in an extremely thin film of gold. This gold layer, only a few millionths of an inch thick, enables the mirrors to best reflect the infrared light the telescope seeks. The thinner the layer, the better off the telescope will be -- every bit of weight counts when a telescope as big as Webb is being lifted into space by a rocket. Join us at Quantum Coating in New Jersey, where engineers are vaporizing gold to apply a thin, even layer to the telescope's mirrors. - HubbleSiteChannel

"Behind the Webb" is an ongoing series that follows the construction of the Webb Space Telescope, Hubble's successor. Find more episodes at

Video Source: HubbleSiteChannel