NASA’s Juno spacecraft launched towards Jupiter in August 2011 and has intently surveyed the gas giant since. Juno has largely contributed to NASA’s understanding of Jupiter but its latest discovery could be the most groundbreaking yet. For the first time ever, NASA has confirmed direct and “definitive” observations of a planet’s changing magnetic field outside of Earth. The process, dubbed secular variation, will hopefully help NASA peel back the layers of Jovian storms and clouds for a better glimpse at Jupiter’s interior.
The NASA discovery has also revealed the side effects powerful winds and atmospheric events have on a planet’s magnetic field.
NASA’s Juno traced the magnetic changes to a particular hotspot near the planet’s equator – the so-called Great Blue Spot.
Scott Bolton, Juno’s principal investigator from Southwest Research Institute in San Antonio, said: “Secular vitiation has been on the wish list of planetary scientists for decades.
“This discovery could only take place due to Juno’s extremely accurate science instruments and the unique nature of Juno’s orbit, which carries it low over the planet as it travels from pole to pole.”
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The Great Blue Spot is an area of intense magnetic activity near Jupiter’s equator, where the secular variation is the strongest.
According to NASA, this incredible spot, which is not visible to the naked eye, drives Jupiter’s changing magnetic field.
Quite bizarrely, NASA found a combination of strong winds and localised magnetic field has a profound effect on the planet as a whole.
Kimee Moore, a Juno scientist from Harvard University, said: “It is incredible that one narrow magnetic hot spot, the Great Blue Spot, could be responsible for almost all of Jupiter’s secular variation, but the numbers bear it out.
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“With this new understanding of magnetic fields, during future science passes we will begin to create a planet-wide map of Jupiter’s secular variation.
“It may also have applications for scientists studying Earth’s magnetic field, which contains many mysteries to be solved.”
NASA’s groundbreaking discovery was made off the back of 40 years worth of Jovian observations, starting with the Pioneer 10 probe in 1972.
What NASA found was small differences in the data collected by Pioneer and the datasets from Juno.
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Ms Moore, a PhD candidate at Harvard, said: “Finding something as minute as these changes in something so immense as Jupiter’s magnetic field was a challenge.
“Having a baseline of close-up observations over four decades long provided us with just enough data to confirm that Jupiter’s magnetic field does indeed change over time.”
The “zonal winds” responsible for the secular variation pass Jupiter’s surface a depths over 1,860 lies (3,000km).
At these latitudes, Jupiter’s gassy composition transforms into a form of highly conductive and liquid metal,
This causes the magnetic fields to sheer and stretch out, casting them all around the planet.