Juno
Solar-powered explorer at Jupiter. NASA's Juno has orbited Jupiter since 2016, studying its storms, magnetic field and moons. How it works and what it has discovered so far.
Juno at Jupiter (artist's concept): NASA/JPL, Public domain
Built for Jupiter
Juno launched in 2011 and reached Jupiter on July 4, 2016. It was the first solar-powered spacecraft sent so far from the Sun, using three huge solar arrays. Its electronics sit inside a titanium vault to shield them from Jupiter's intense radiation.
What Juno found
Juno's looping polar orbits gave the first close views of Jupiter's poles, revealing clusters of giant cyclones arranged in geometric patterns. Gravity measurements showed that Jupiter's core is large and fuzzy rather than small and compact, and that its famous belts and zones extend thousands of kilometres deep.
It has also mapped Jupiter's powerful magnetic field and studied its auroras, the most powerful in the solar system.
Moons up close
In its extended mission, Juno flew past Ganymede in 2021, Europa in 2022 and Io in December 2023 and February 2024, taking the closest images of Io in two decades and spotting lava lakes. NASA extended the mission into the mid 2020s.
Juno is named after the Roman figure who, in the old story, could see through the clouds that Jupiter drew around himself, a neat match for a spacecraft that peers beneath Jupiter's cloud tops.
A public camera
JunoCam was included mainly for public engagement. NASA posts the raw images online, and amateur image processors around the world turn them into the swirling colourful portraits of Jupiter that often go viral. Some of the best-known Jupiter images of the past decade were made this way.
Why Jupiter matters
Jupiter is the oldest and biggest planet, and its formation shaped the orbits and makeup of everything else in the solar system. Learning how much water it holds, how its core formed and how deep its winds go helps scientists understand how giant planets form around other stars too. Juno's measurements of the atmosphere and the structure of the interior are key pieces of that puzzle.
Juno also carries three small figures made of aluminium, representing Galileo and the Roman characters Jupiter and Juno, built to survive the long trip.
- Juno at Jupiter (artist's concept): NASA/JPL, Public domain
Text written by Planetinio.
