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Solar storms ignite Jupiter’s auroras

For the first time, Jupiter’s auroras have been studied in X-ray light when a giant solar storm arrived at the planet.

Artist's concept of Jupiter moving through the solar system and interacting with a powerful CME from our sun, which creates an aurora at Jupiter.  Image via University College London.

Artist’s concept of Jupiter moving through the solar system and interacting with a powerful CME from our sun, which creates an aurora at Jupiter. Image via University College London.

Solar storms trigger X-ray auroras on Jupiter that are about eight times brighter than normal over a large area of the planet and hundreds of times more energetic than Earth’s northern lights.

That’s according to a new study published March 22, 2016 in the Journal of Geophysical Research. The research – using data from NASA’s Chandra X-ray Observatory – is the first time Jupiter’s auroras have been studied in X-ray light when a giant solar storm arrived at the planet.

This is a Hubble Space Telescope image of Jupiter - with the strength of X-ray auroras October 2, 2011 indicated.  The Chandra X-ray observatory found these auroras to be about 8 times brighter than normal over a large area of the planet. Image credit: X-ray – NASA / CXC / UCL / W. Dunn et al.; Optical – NASA / STScI.

This is a Hubble Space Telescope image of Jupiter. The strength of X-ray auroras on October 2, 2011 are superimposed to create this composite image. The Chandra X-ray observatory found the auroras on this day to be about 8 times brighter than normal over a large area of the planet. Image credit: X-ray – NASA / CXC / UCL / W. Dunn et al.; Optical – NASA / STScI.

The sun constantly ejects streams of particles into space in the solar wind. Sometimes, giant storms, known as known as coronal mass ejections (CMEs), erupt and the winds become much stronger. These events compress Jupiter’s magnetosphere, the region of space controlled by Jupiter’s magnetic field, shifting its boundary with the solar wind inward by more than a million miles.

This new study suggests that the interaction at the boundary triggers the X-rays in Jupiter’s auroras, which cover an area bigger than the surface of the Earth.

William Dunn is PhD student at University College London’s Mullard Space Science Laboratory and the study’s lead author. Dunn said:

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.

The impact of solar storms on Jupiter’s aurora was tracked by monitoring the X-rays emitted during two 11-hour observations in October 2011 when an interplanetary coronal mass ejection was predicted to reach the planet from the sun. The scientists used the data collected to build a 3D spherical image to pinpoint the source of the X-ray activity and identify areas to investigate further at different time points. Dunn said:

In 2000, one of the most surprising findings was a bright ‘hot spot’ of X-rays in the aurora which rotated with the planet. It pulsed with bursts of X-rays every 45 minutes, like a planetary lighthouse.

When the solar storm arrived in 2011, we saw that the hot spot pulsed more rapidly, brightening every 26 minutes. We’re not sure what causes this increase in speed but, because it quickens during the storm, we think the pulsations are also connected to the solar wind, as well as the bright new aurora.

The findings comes NASA’s Juno spacecraft nears Jupiter for the start of its mission this summer. Launched in 2011, Juno aims to unlock the secrets of Jupiter’s origin, helping us to understand how the solar system, including Earth, formed. As part of the mission, Juno will investigate Jupiter’s relationship with the sun and the solar wind by studying its magnetic field, magnetosphere and aurora.

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Bottom line: A study published March 22, 2016 in the Journal of Geophysical Research using data from NASA’s Chandra X-ray Observatory suggests that solar storms trigger X-ray auroras on Jupiter that are about eight times brighter than normal over a large area of the planet and hundreds of times more energetic than Earth’s northern lights.

Read more from University College London

Eleanor Imster

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