Over the past 40 years, the two Voyager spacecraft have explored Jupiter, Saturn, Uranus and Neptune. They have sent back detailed views of these strange worlds, revealing moons encased in ice, covered in volcanoes and bathed in gasoline smog. The missions have changed our perspective on the Earth and, with golden gramophone records attached to their sides, are now taking human culture to the stars.
Remarkably, both Voyager spacecraft are still working. Whenever Voyager 1 sends back a signal, it is from the furthest distance any human-made object has travelled from Earth.
Voyager 1 left the solar system in 2013 and is (at the time of writing) 20 billion kilometres (12 billion miles) away. Voyager 2, on a different trajectory, is 17 billion kilometres (10.5 billion miles) away. Maybe it’s easier to imagine it like this: it takes a radio signal, travelling at the speed of light, 38 hours to travel from the Earth to Voyager 1 and back. And it’s some 30 hours for Voyager 2. (For their latest position, visit the Voyager home page.)