I think they just made up names for the colors. Starlight black, Solar gold, Mayan red, Atlantis blue, Nocturne blue....somebody at Pontiac marketing just decided on an imaginative name for the colors that were used on Pontiacs at the time. It made the choice of color more interesting to the buyer and made for nice reading in the dealer brochure. I don't think it's any more complicated than that.
And sometimes the different GM divisions made up their own names for the colors, even though they often used the exact same color. For example, Chevrolet's Hugger Orange is the same paint code as Pontiac's Carousel red.