Rosie Johnson

2016 AFPGR Participant


Mapping of Jupiter’s Infrared Aurora
About Rosie
Rosie is a research student working towards completion of her doctoral degree with the Radio and Space Plasma Physics research group in the Department of Physics and Astronomy. Her supervisors are Tom Stallard and Jonathan Nichols. After being successful in an observing proposal, Rosie was awarded time at the NASA Infrared Telescope Facility in Hawaii to observe Jupiter’s auora during the approach phase of the Juno mission. During her time observing in Hawaii, Rosie wrote a blog which you can access via Rosie is a mentor for Space School UK, a week long residential summer school, hosted by the University of Leicester, aimed at space enthusiasts of secondary school age ( On 9th July 2016 Rosie will be taking part in Soapbox Science Milton Keynes event, which is a street art form of outreach with the aim of raising the profile of women in STEM ( Profile portrait image
About My Research

I study the infrared aurora of Jupiter using data from the Very Large Telescope (VLT), Chile, and the NASA Infrared Telescope Facility (IRTF), Hawaii. At each of these telescopes there is an instrument available that can split the light observed from Jupiter into separated wavelengths. This makes it possible to study the infrared aurora created by a charged molecule or ion, known as , that exists in Jupiter’s upper atmosphere. By using the instrument to scan Jupiter’s northern hemisphere, we can build up images of the aurora, which can be projected onto a map. We can calculate the velocity of the charged molecules through the principal of Doppler shift, which is the change in wavelength of the light emitted by the charged molecule as it moves around in the upper atmosphere of Jupiter. The velocity can also be projected onto a map and then compared to the mapped aurora intensity.

We study Jupiter’s aurora because we are interested in discovering the effect of space weather on Jupiter. Particles are constantly flowing away from the Sun, dragging with them the Sun’s magnetic field, and together they are known as the solar wind. Conditions in the solar wind often change and this variability is known as space weather. Jupiter’s magnetic field is 10 times stronger than the Earth’s, and expands into a bubble surrounding Jupiter known as a magnetosphere. Jupiter’s magnetosphere rotates quickly and is filled with charged molecules from the volcanic moon Io. Exactly how the solar wind and Jupiter’s magnetosphere interact with each other is not known.

With the progression into the space age, a good understanding of space weather and its influence on the Earth and other planets is paramount. Studying Jupiter’s aurora and the effect of space weather can not only be applied to the Earth-Sun system, but it also prepares us for future space exploration and the potential industrialisation or colonisation of Jupiter's moons.

Jupiter’s infrared aurora _Rosie Johnson
Jupiter’s infrared aurora – image credit: J. Connerney, NASA Goddard

My festival presentation
At the festival of post graduate research I will be presenting the work I have recently completed with the data from the VLT. Using this data, I have created maps of the aurora and the associated velocities of the charged molecules that create the infrared aurora. From these maps we have discovered that part of Jupiter’s aurora is connected to the solar wind, which means Jupiter’s aurora is influenced by the solar wind. However, it is yet to be discovered how the aurora is connected to the solar wind and this remains a controversial topic in space physics.

My research findings

Prior to completing the work on the data from the VLT, I submitted a paper which investigates the low latitude emission in Jupiter’s upper atmosphere in the equatorial region far away from the aurora. It is often assumed that the charged molecules in the equatorial region will have a velocity which means they move at the same rate as the planets rotation. This assumption is very important for modelling the aurora and our current understanding of Jupiter’s magnetosphere. However no previous studies have measured the velocities of the charged molecules at in the equatorial region. By using data from IRTF, I calculated the velocity of the charged molecules and found them to be rotating with the planet, in agreement with the common assumption.

After submitting a proposal to observe Jupiter’s aurora at IRTF I was awarded 8 nights of observations spread out over 5 weeks from February to March 2016. During these observations the NASA space craft Juno was travelling to Jupiter and monitoring the space weather close to Jupiter.  The means we can compare our measurements of the aurora with the solar wind measurements taken by Juno. At the same time, a JAXA satellite, Hisaki was monitoring the volcanic output from Io (Jupiter’s volcanic moon). By using these simultaneous observations we will be able to separate the effects of space weather and volcanism on Jupiter’s aurora and discover how they create Jupiter’s aurora.

The VLT data that I will present at the Festival of Post Graduate Research is a case study from one night of observations. Additional data from IRTF was taken over several months by my supervisor, which I will use alongside the VLT data to further our understanding of how space weather affects Jupiter over longer time scales.

Finally, I am currently waiting to hear about a telescope proposal which I submitted in April 2016. If I am successful in receiving this telescope time then I will be observing Jupiter’s aurora at the same time Juno is also observing Jupiter’s aurora and taking measurements from inside Jupiter’s magnetosphere!

Presenter_Rosie Johnson
Rosie with her poster at the 2016 Festival of postgraduate Research

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