Voyager 2 made its closest approach to Jupiter

On July 9, 1979, NASA’s Voyager 2 made its closest approach to Jupiter, flying within about 350,000 miles of the planet’s cloud tops. Arriving four months after its twin, Voyager 1, the spacecraft acted as a second pair of eyes on a world that had just upended scientists’ expectations.

Voyager 2 ran a 10-hour volcano watch of the moon Io, confirming Voyager 1’s startling discovery of active volcanoes — the first ever seen beyond Earth. It also backlit and imaged Jupiter’s faint ring system, and returned high-resolution views of Europa, whose cracked, marbled surface hinted at a frozen crust over a deep ocean.

Voyager 2 confirmed that Io’s eruptions were not a fluke — the moon was, and is, the most volcanically active body in the solar system.

The flyby also bagged a previously unknown moon, Adrastea. Jupiter’s gravity then slingshotted the probe toward Saturn, continuing a grand tour that, decades on, carried it into interstellar space.