Launched in 1977, Voyager 1 has been traveling through space for nearly half a century—yet it still hasn’t completed even a single light-day of distance. Despite being the farthest human-made object from Earth, this fact powerfully demonstrates just how unimaginably vast space truly is. Voyager 1 travels at about 17 kilometers per second, a speed that would circle Earth in minutes. But light moves so fast that one light-day equals nearly 26 billion kilometers. Even after 48 years of continuous t