How many times greater is the distance to Alpha Centauri than the distance to the Moon?
The average distance to the moon from Earth is about 1.30 light seconds, while the distance to the closest star in the Alpha Centauri system (Proxima Centauri) is about 4.23 light YEARS. The fastest outward-bound spacecraft yet sent, Voyager 1, has covered 1/600th of a light-year in 30 years and is currently moving at 1/18,000th the speed of light. At this rate, a journey to Proxima Centauri would take 72,000 years. Of course, this mission was not specifically intended to travel fast to the stars, and current technology could do much better. The main difficulty of interstellar travel is the vast distances that have to be covered and therefore the time it takes with most realistic propulsion methods—from decades to millennia. Hence an interstellar ship would be much more severely exposed to the hazards found in interplanetary travel, including hard vacuum, radiation, weightlessness, and micrometeoroids. The travel time could be reduced to a few millennia using lightsails, or to a centur
