NASAs Juno Finds Great Blue Spot Affects Jupiters Entire Magnetic Field

NASA's Juno Mission to Jupiter finds that the Great Blue Spot affects the entire magnetic field

Published on 25th May, 2019

Space Fan News is Sponsored by OPT Telescopes and Patreon Patrons: Hello Space Fans and welcome to another edition of Space Fan News. In this episode, it’s time to check in with an old friend: the Juno spacecraft currently orbiting Jupiter has reached a science milestone this week with stupendous news about the magnetic field of the largest planet in our solar system. We’ve been following NASA’s Juno mission to Jupiter ever since it arrived in orbit around the Jovian planet in July 2016 with the stated mission of learning more about the composition, gravity field as well as the magnetic field of this colossal planet. The spacecraft is in a polar orbit that’s designed to get it really close to the upper layers of the atmosphere in part so it can use the onboard magnetometers to measure the magnetic field as accurately as possible. Each time Juno swings by Jupiter it takes readings and send them back to earth. This is the closest we’ve ever been to Jupiter and the first magnetic field data we’ve been able to get since Pioneer 10 and 11, Voyager 1 and the Ulysses probe and Juno’s magnetometers are way more sensitive than anything that’s come before. So earlier this week, it was with great excitement that from the data collected from the first eight science passes of Juno with Jupiter, that team members announced their first findings about Jupiter’s magnetic field from the mission. It turns out that Jupiter does in fact have an internal magnetic field that changes over time, something called secular variation. And what’s really cool about it is that this changing magnetic field is most likely driven by the planet’s deep atmospheric winds. By comparison, the Earth also has a magnetic field that changes with time but is driven by the convection deep within the molten metal core of our planet, something they call a dynamo. This magnetic field is hugely important to us because it protects life on Earth from radiation of the Sun bombarding and killing us. So magnetic fields are very interesting things for planets to have. But it appears that the magnetic field of Jupiter is driven by the atmosphere, which makes a lot of sense given that Jupiter has so much of it. This magnetic field changes in small but distinct ways that Juno’s sensitive instruments were able to pick up. This was hard to do because the magnetic field of the Jovian planet is just so huge, but by adding Juno’s data to the previous spacecraft measurements takes over four decades provided just enough data to confirm that Jupiter’s magnetic field does indeed change over time. Once they found out the field was changing, the next big question was what was causing it. They found that the zonal winds of Jupiter, which extend from the planet’s surface to over 3,000 kilometers deep where the interior changes from gas to liquid metal, could cause the changes they were seeing. These winds - some of which include liquid metal - could shear the magnetic fields and stretch and carry them around the planet. But check this out, nowhere was the change in magnetic field larger than in this one spot on Jupiter. Called the Great Blue Spot, and invisible to the visible wavelengths our eyes can see, is an area of intense concentration of magnetic energy. This region is near the equator of Jupiter where some of the strongest zonal winds exist and this area was a surprise. It appears that almost all of Jupiter’s magnetic field changes are coming from this Great Blue Spot. So this was a big deal for Juno scientists because it marked a scientific milestone for the mission, measuring these magnetic field lines was one of the reasons we sent Juno to Jupiter in the first place. Now, with this new understanding of the Jovian magnetosphere, they are going to try to build a planet wide map of Jupiter’s secular variation from future science passes and continue to compare what’s going on here with the Earth’s magnetosphere, you never know what insights they might bring. Well that is it for this episode Space Fans, thanks to you lovely Deep Astronomy Patreon Patrons who make sure SFN keeps coming, and OPT Telescopes a world leader in telescopes and accessories for both amateur and professional astronomers. Thanks to all of you for watching and as always, Keep Looking Up!