Voyager spacecraft, illustration. Voyager 2 is the only space probe to have visited Uranus and Neptune. It was launched in August 1977 as part of an ambitious exploration programme to study the outer planets (Jupiter, Saturn, Uranus and Neptune). Its twin, Voyager 1, was launched one month later in September 1977, at a greater speed that allowed it arrive at Jupiter and Saturn before Voyager 2. The probes explored both planets between 1979 and 1980, but Voyager 2 also visited Uranus and Neptune in 1986 and 1989 respectively. In August 2012 and November 2018 Voyager 1 and 2 respectively left the Solar System and moved into interstellar space, becoming the most distant man-made objects in space.