Multi Layer Insulation can look like metal foils, but it's more complicated and indeed much better at its job of keeping the spacecraft at the right temperature. The outermost layer is commonly made of a yellow polymer named 'Kapton' and when a metal layer is deposited on the back surface it can appear to be a gold colour.
Insulation blankets in spaceflight generally use this design, even if the outer layer is covered by a more traditional looking fabric. The blankets are exceptionally efficient at maintaining thermal control.

Here's a great video showing the construction of such a multi layer insulating blanket:
https://hpf.psu.edu/2014/09/29/mli-bl...

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