The University of Leicester is in the front row of research as the Great Red Spot (GRS) shrinks

The largest planet in our Solar System, Jupiter, is best known for the colourful storms in its atmosphere, the most famous being the Great Red Spot (GRS). The spot is made up of red swirling clouds travelling anti-clockwise that have battered Jupiter for the past 188 years. The atmosphere surrounding Jupiter carries powerful jet streams reaching up to 400mph and consequently keeps “feeding momentum into the vortex” according to Glenn Orton, a Juno mission team member. It is because of this atmosphere that allows storms to persist for hundreds of years, unlike Earth.

However all seems about to change as scientists including those from the University of Leicester have found that the spot is reducing in size and could be on the brink of disappearing for good, despite the fact it was once 4 times the size of Earth. In April 2017 the Juno spacecraft passed the planet and captured the closest images of the storm to reveal how much the spot has reduced in size, suggesting it could be within less than two decades of fading away.

These images are the closest a spacecraft has ever been to a planet, as for the first time we are able to see below the dense cover of clouds, gaining us access to ground-breaking new data. The spacecraft is also the first of its kind to be solar powered, and allows us to take the highest-resolution images of the planet ever recorded in history. The mission will allow us to understand the origin and evolution of Jupiter, with the University of Leicester’s Department of Physics and Astronomy having a significant part to play in the mission.

The University is home to the only formal UK science lead involved in the mission.

Professor Stan Cowley was given the position of co-investigator on the main Juno team due to the research into Jupiter that the University had carried out prior to the mission’s launch. The research was carried out involving the theoretical study of Jupiter’s environment, which was then published in 2001, the paper became the definitive model for how we anticipate Jupiter’s auroras are generated. NASA then got in touch with the University to collaborate in planning the mission and data analysis to follow.

Since arriving in July 2016, Juno has been orbiting Jupiter over a 14 day cycle and comes with three main intentions. It is delving deeper into the formation of the planet by studying the internal structure through measuring composition, temperature, and water content. Atmosphere is the second focus, looking at cloud motions including structures such as the GRS and the magnetic and gravitational fields. Finally the beautiful auroras are an aspect to the planet that Jonathan Nichols from the University describes as a “firework party” due to the luminous sights and colours that are created around Jupiter.

Auroras are created by electrons and protons colliding with atoms and molecules of gas in the atmosphere, resulting in colourful beams of light, brighter than ultraviolet. Nichols goes on to add how Jupiter’s auroras are of significant interest because they are “very dramatic and among the most active I have ever seen”. The University team have been able to study the auroras closely using the Hubble Space Telescope, revealing stunning light shows in the planet’s atmosphere resulting in new data, something “extremely exciting” according to Dr Klaas Wiersema from the University.

Not only is the University responsible for the Juno mission’s planning and predictions, but also had a large part to play in the Cassini spacecraft launched by NASA to study Saturn, Jupiter’s smaller neighbour. They looked at the surrounding atmosphere alongside the auroral display created too. It may be smaller than Jupiter, but the relevant experience will only add to the depth of knowledge needed for the data analysis of the Juno mission being carried out now that it has well and truly started.

The spot, now 1.3 times the size of Earth, has diminished by one-third since NASA passed by Jupiter to reach Saturn in 1979. Glenn Orton revealed how “the GRS has been shrinking for a long time” and that “nothing lasts forever”. The spot will continue to shrink and is suspected to have disappeared by 2038, for now though, the University of Leicester team alongside NASA will continue to study Jupiter closely to increase the understanding of our surrounding solar system.

· More information on the University’s involvement in the mission can be found here · Juno mission webpage

India Wentworth

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