NASA's Juno spacecraft will get its closest look yet at Jupiter's moon Io on Dec. 30

An illustration shows NASA's Juno spacecraft as it makes a flyby of the Jovian moon Io.

NASA's Juno mission will come closer to Jupiter's moon Io than any spacecraft has in around 20 years on Saturday (Dec. 30).

The flyby will bring Juno to around 930 miles (1,500 kilometers) of Io, the most volcanic body in the solar system. This will allow the spacecraft to take a detailed look at Io as it gathers a treasure trove of hot data. It's close, but not the closest ever glimpse by a spacecraft: that record belongs to NASA's Galileo spacecraft, which skimmed just 181 kilometers (112 miles) above Io's south pole in 2001.

Juno launched on August 5, 2011, and reached the gas giant Jupiter, the largest planet in the solar system, on July 4, 2016, after a 1.7 billion-mile (2.8-billion-kilometer) journey. Since then, the Jupiter orbiter has made 56 flybys of the gas planet, collecting data on it and its moons, and is about to begin its next.