The October 1945 edition of Wireless World magazine carried an article from a young Arthur C. Clarke called “Extra Terrestrial Relays.” It was the concept of using satellites in geostationary orbit, 35,786 kilometres high, around the Earth, to beam radio signals from one continent to another. Remember Sputnik didn’t go into orbit until October 1957, and that only reached a height of 577km. So in 1945 the article was received as a grand idea, theoretically possible, but by the standards of post WWII rocketry, severely impractical. Nonetheless, the first communication satellite to use this orbit (now named the Clarke Orbit) was Syncom 3, launched in August 1964, 19 years after Clarke’s article. An article which was detailed enough to receive a patent had he sent it to the patent office instead of the magazine. Today, communication satellites are a multi-billion pound business.
Clarke drew together a number of sciences—orbital mechanics, radio design, rocketry—and extrapolated the combination perfectly. It’s one of the best examples of what people see as a Science Fiction writer’s job: predicting the future.