Show him the 1958 It! The Terror From Beyond Space. It predates TAS by 15 years and is much more Alien like. Then there's Mario Bava's 1965 Terrore nello spazio (Planet of the Vampires), which has a lot of additional similarities.I finally picked up the TAS set at Walmart ($14.99). My oldest son an I sat down to watch the first episode ("Beyond the Farthest Star") and he was suitably impressed. Halfway through, he turned to me and said "Did the movie Alien rip this off?" There are actually quite a few similarities.