That color comes from compounds called " tholins" formed when hydrocarbons in Pluto's atmosphere are zapped with ultraviolet radiation and then rain down onto the surface.

这种颜色来自于冥王星大气中的碳氢化合物被紫外线辐射照射后雨滴落到地表时形成的称为“tholins”的化合物。

We think the Brass Knuckles get their  dark colour from a tar made of tholins, which are hydrocarbons formed from the interaction  of methane and nitrogen with cosmic rays.

我们认为指节铜套的深色来自由托林制成的焦油，托林是甲烷和氮气与宇宙射线相互作用形成的碳氢化合物。