The Voyagers are a pair of unmanned US space probes, launched to explore the outer planets.
Voyager 1 was launched on 5 September 1977. It flew past Jupiter in March 1979 and Saturn in November 1980, and then headed onwards on a curved path that will take it out of the Solar System altogether.
Voyager 2 travels more slowly. Although launched two weeks earlier than Voyager 1, it did not reach Jupiter until July 1979 and Saturn until August 1981.
The Voyagers used the ‘slingshot’ of Jupiter’s gravity to hurl them on towards Saturn.
While Voyager 1 headed out of the Solar System, Voyager 2 flew past Uranus in January 1986 and Neptune on 24 August 1989. It took the first close-up photographs of the two planets.
The Voyagers revealed volcanoes on Io, one of Jupiter’s Galilean moons.
Voyager 2 found ten unknown moons around Uranus.
Voyager 2 found six unknown moons and three rings around Neptune.
Voyager 2 discovered sulphur volcanoes on Jupiter, in 1979.
Voyager 2 reached Neptune in 1989, revealing a wealth of new information about this distant planet. Space travel Voyager 2 will beam back data until 2020 as it travels beyond the edges of the Solar System.