Jupiter's Great Red Spot storm, as seen by NASA's Juno spacecraft. Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin Gill


NASA’s Juno spacecraft has entered Jupiter’s magnetosphere on its way to study the planet.

The event marks the spacecraft’s entry into the area where particles in space are influenced by Jupiter’s atmosphere.

Juno’s science instruments detected changes in the particles around the spacecraft as it entered the magnetosphere.

A NASA video explaining how Juno will analyse Jupiter’s magnetospher. Credit: NASA/Goddard/Daniel Gallagher

Data collected by Juno shows it crossed the bow shock just outside the magnetosphere on 24 June, passing into the magnetosphere a day later.

This bow shock is created as solar winds - streams of charged particles released by the Sun - hit the magnetospheres of planets, creating a massive turbulence.

While passing through the solar wind, Juno was travelling through an environment containing about one particle per cubic centimetre.

Once it passed into the magnetosphere, the environment’s density dropped by about 100 times.

Juno will be able to measure conditions within this magnetosphere to analyse what is going on in Jupiter’s atmosphere and how its magnetic field is generated.

Data already sent back during this phase has revealed unexpected results.

It shows that the structure of the boundary between the two regions is more complex than expected, and will require analysis by NASA scientists back on Earth.

Juno is expected to arrive at the planet's orbit on 4 July, where it will begin analysis of the planet itself.

"We've just crossed the boundary into Jupiter's home turf," says Juno Principal Investigator Scott Bolton of Southwest Research Institute.

"We're closing in fast on the planet itself and already gaining valuable data."

“I view Jupiter as a missing link,” says Barry Mauk of Johns Hopkins University Applied Physics Laboratory.

“Jupiter is the link between the nearby space environments we study at planets like Earth, and distant astrophysical systems where magnetic fields hold sway, such as early-stage star forming regions, and hyper-energetic radiation regions like the Crab Nebula.


Juno is not only going to help us better understand Jupiter, it’s going to help us better understand the Universe around us and our place in it.”