NASA’s Jet Propulsion Laboratory recently released another batch of gorgeous space travel posters to whet your appetite for interplanetary tourism. Included in the group is an advertisement for Jupiter with the caption, “Experience the mighty aurora.” Jupiter is well known for having some of the most extreme aurora events in the solar system. They are so large they cover as much as the entire surface area of the Earth and are 100 times more energetic than Earth’s ‘northern lights’. This week, scientists published new findings in the Journal of Geophysical Research: Space Physics about what might be creating these spectacular events and the culprit seems to be our sun. Using NASA’s Chandra X-Ray Observatory, scientists were able to observe a solar storm arriving at Jupiter and watch how it affected the planet.
The sun is a massive star, and it’s a pretty active place. There are storms and events in this colossal furnace on a daily basis. However, when the sun emits what’s known as a Coronal Mass Ejection (CME), it releases a huge amount of energy. This type of ejection creates a much stronger solar wind that bumps up against Jupiter’s magnetosphere. Jupiter has the largest magnetic field in the solar system, so large in fact that it stretches out 7 million kilometers beyond the surface. After an event like a CME, intensely charged solar particles blaze through the solar system–and when they arrive at Jupiter’s magnetosphere, a battle takes place between those particles and the planet’s magnetic field.
William Dunn, lead author of the recent paper and scientist at UCL Mullard Space Science Laboratory, explains, “There’s a constant power struggle between the solar wind and Jupiter’s magnetosphere. We want to understand this interaction and what effect it has on the planet. By studying how the aurora changes, we can discover more about the region of space controlled by Jupiter’s magnetic field, and if (or how) this is influenced by the Sun. Understanding this relationship is important for the countless magnetic objects across the galaxy, including exoplanets, brown dwarfs, and neutron stars.”
When the solar storm arrived at Jupiter in 2011, Dunn and his colleagues noticed that the power of the solar wind actually reshaped Jupiter’s magnetic field by 2 million kilometers. The changes in the aurora were monitored by looking at X-Rays emitted over two eleven-hour observations after a CME was predicted to leave the sun and arrive at the planet’s magnetosphere boundary. Scientists were surprised to see a regular pulsing of X-rays in the aurora after the storm arrived.
More recently, a different team from the Japan Aerospace Exploration Agency (JAXA) released new data also looking at the interaction of solar wind and the Jupiters’s magnetic field. They found that despite the absence of a CME, even the faintest gusts of solar wind still affected the aurora at Jupiter’s poles. This latest result strengthened the connection between the two events.
All of these findings are just in time for NASA’s Juno spacecraft to arrive at Jupiter this July. A major goal of JUNO’s mission will be to understand the nature of Jupiter’s magnetic field and gravity fields, and how both of these might be affected by different cosmic events. JUNO has been en route to Jupiter since August of 2011 and will arrive almost five years later. JUNO will orbit around the poles as it studies the aurora and magnetic field activity. Interest in Jupiter’s aurora has been commonplace ever since Voyager 1 sent back images in 1979. Scientists have been wondering ever since exactly what is going on with the planetary giant and as the JUNO mission approaches, we are sure to find out some pretty interesting facts.