Human civilizations' longest lasting artifacts are not the great Pyramids of Giza, nor the cave paintings at Lascaux, but the communications satellites that circle our planet. In a stationary orbit above the equator, the satellites that broadcast our TV signals, route our phone calls, and process our credit card transactions experience no atmospheric drag. Their inert hulls will continue to drift around Earth until the Sun expands into a red giant and engulfs them about 4.5 billion years...
