Which Voyager space probe launched first?

Voyager 1 is a space probe launched by NASA on September 5, 1977. Part of the Voyager program to study the outer Solar System, Voyager 1 launched 16 days after its twin, Voyager 2. Having operated for 38 years, 8 months and 15 days, the spacecraft still communicates with the Deep Space Network to receive routine commands and return data. At a distance of 135 AU (2.02×1010 km) as of May 2016, it is the farthest spacecraft from Earth and the only one in interstellar space.

The probe's primary mission objectives included flybys of Jupiter, Saturn, and Saturn's large moon, Titan. While the spacecraft's course could have been altered to include a Pluto encounter by forgoing the Titan flyby, exploration of the moon, which was known to have a substantial atmosphere, took priority. It studied the weather, magnetic fields, and rings of the two planets and was the first probe to provide detailed images of their moons.