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Astronaut visors use a thin gold layer to decrease intensity of IR radiation coming from the sun. The thing is, gold is a conductive surface, so how can it transmit light through it. Is this related to the skin effect, where an AC current running through a wire will cause current to build up of surface of the wire?

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    $\begingroup$ What does gold being a conductor matter? If conductors of arbitrary thinness blocked arbitrary EM radiation then metal foil would be the perfect radiation shield... $\endgroup$
    – ACuriousMind
    May 17 at 15:57
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    $\begingroup$ How much light is absorbed by one gold atom? How about two? There is a skin depth, and if a gold layer is thinner than the skin depth then you have transmission. $\endgroup$
    – Jon Custer
    May 17 at 16:00

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Sufficiently thin gold films are not opaque but green:

This is near the percolation threshold at which clumps or islands of atoms join to form a continuous opaque film. See also Norrman et al. (1978). "Optical properties of discontinuous gold films," Phys Rev B 18, 674, and Turner, T. (1908). "Transparent silver and other metallic films," Proc R Soc Lond A, 81, 301–310, and the references within. As noted, Michael Faraday may have been the first to report this behavior, realized by inspecting through-illuminated beaten metal films.

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