Voyager 1 Forever Changed Jupiter Views Before Its Light-Day Mark

By then the probe had already taken tens of thousands of images of the outer solar system. Some of them transformed scientists' understanding of the outer planets.

What the Jupiter flyby showed

Voyager 1 observed Jupiter from January to April 1979. According to NASA, it came within 174,000 miles (280,000 km) of the planet in March 1979.

On approach, the probe photographed the gas giant every 96 seconds. The frames became a time-lapse movie of Jupiter's turbulent atmosphere. Discrete bands spun at different speeds and in different directions, clouds raced past, and planet-size storms swirled.

The film captures about 60 full days on Jupiter. Each Jupiter day lasts roughly 10 Earth hours, so that equals about a month on Earth. It gave the most comprehensive and high-resolution look at the planet to date.

It also built on data from NASA's Pioneer 10 and 11 probes, which launched half a decade earlier. Together the data showed an atmosphere much more dynamic than astronomers had realized.

Rings and a volcano on Io

Just before its closest approach, Voyager 1 spotted a thin, faint ring system around Jupiter. The rings are made mainly of dust, and they appeared only when Voyager saw Jupiter backlit by the sun.

No telescope had seen them before. Ground-based observatories soon confirmed they existed, and Voyager 2 took clearer pictures when it reached Jupiter in July 1979.

Jupiter, Saturn, Uranus and Neptune are now all known to have rings. Scientists suspect volcanic eruptions on Jupiter's moon Io partly replenish Jupiter's dusty rings.

During its close approach to Io, Voyager 1 also witnessed the first volcanic eruption ever seen on a world beyond Earth. One image shows Loki Patera, the largest volcano on Io, estimated at 125 miles (200 km) wide. The sighting showed that moons, not just planets, can be geologically active.

The close-up views turned Jupiter and its moons from dots in the sky into fully realized worlds. This week, China's space agency announced its intention to send a lander to Jupiter's moon Callisto, in the first-ever landing mission to the Jovian system.

What Voyager 1 does now

With its camera off, Voyager 1 studies the radiation environment of space using magnetic field and plasma detectors. They are the last two of its 10 science instruments still receiving power.

Scientists suspect the probe will fully run out of power in the 2030s.