The Topps company issued a trading card set in the 1950's that is known by two names: Space Cards and Target: Moon. The fronts of both sets of cards are identical, with the backs nearly so; the only difference was the set name given at the bottom of the card back. There were 88 cards in the set.
Card fronts depicted a painting of a futuristic, sci-fi subject, with the card title in a thin horizontal oval superimposed over it. Card backs featured an outer-space background in light blue ink; the card number was given in a small Sputnik-shaped block at the upper left. (Speculation is that this set was released in 1957, which was indeed when Sputnik, and the American mania for all things space-related, made their debuts.) The card title and a short paragraph about the image on the card front were situated within an oval shape against the background. The set name - either SPACE CARDS or TARGET:MOON - was below this.
Both 1-cent and 5-cent wrappers are known to exist, virtually identical between the two card sets, but with slight coloring differences.
The American Card Catalog reference number for Space Cards is R714-20a; for Target: Moon, it's R714-20b.
To further confuse collectors, individual Target: Moon cards were issued as Popsicle premiums in 1958; these feature the Popsicle logo and have pink backs. Also, a British version of Space Cards was issued.