On August 20, 1977, Voyager 2 was launched from NASA’s facility in Cape Canaveral, Florida. And exactly 15 days later, on September 5, 1977, Voyager 1 was launched from the same facility. The timing was crucial because astronomical calculations had placed Jupiter, Saturn, Uranus and Neptune in a lineal alignment that would only occur once every 176 years. With this alignment, each planet could accelerate the two spacecrafts to their next destination, reducing the travel time from 30 years to 12 years.