Voyager 2 is the only spacecraft to visit all four giant planets.
NASA launched Voyager 2 on 20 August 1977. A rare planetary alignment allowed it to travel past Jupiter, Saturn, Uranus, and Neptune, completing the only close-up reconnaissance of Uranus and Neptune so far conducted by a spacecraft.
Voyager 2 flew past Jupiter in 1979, Saturn in 1981, Uranus in 1986, and Neptune in 1989. Its observations revealed active weather, new moons, rings, and unexpected magnetic environments across the outer Solar System.
Voyager 1 also explored Jupiter and Saturn, but its trajectory took it northward away from Uranus and Neptune. Voyager 2 later entered interstellar space, although its planetary grand tour remains the achievement that distinguishes it from every other probe.