On June 13 , 1983 , the craft crossed the orbit of Neptune , the outermost planet .
On June 13 , 1983 , the craft so became the first human - made object to leave the proximity of the major planets of the Solar System .
On June 13 , 1983 , the craft crossed the orbit of Neptune , the outermost planet , and so became the first human - made object to leave the proximity of the major planets of the Solar System .