Jupiter’s Stormy Palette

Despite multiple studies, scientists have not yet been able to determine the cause for Jupiter’s colors. Parts of Jupiter are whitish, or brownish, or some other color in a similar scheme. The Great Red Spot (GRS) is, well, not very cleverly named. Wide enough to fit two Earths across it, the GRS is a massive storm that has been raging for at least 150 years.
Jupiter’s GRS is hosted in the South Tropical Zone, about 20 to 30 degrees south latitude, usually whitish in color. The GRS is also not the only anticyclone (weather system surrounding an area of high pressure, with counterclockwise air circulation in the southern hemisphere) in this area. Some of the other storms form near the GRS. Usually they form and either grow on their own and merge with other storms, and sometimes interact with the GRS. Usually, the GRS acts to swallow the South Tropical Oval (STrO) and the smaller storm falls apart.
A close-up of Jupiter's Great Red spot and swirling clouds, taken by Voyager 1. Image credit NASA/JPL.
A close-up of Jupiter’s Great Red spot and swirling clouds, taken by Voyager 1. Image credit NASA/JPL.
The majority of STrOs are whitish in color, surrounded by a darker ring. It is for this reason that one particular anticyclone caught the eye of scientists; it was reddish. Dubbed the Red Oval (RO), this storm appeared in early 2008. Sixty degrees longitude west of it was a similar storm–but it is white in color. What’s up with that?
Published in 2013 in the American Geophysical Union’s Journal of Geophysical Research: Planets, authors A. Sánchez-LavegaJ. LegarretaE. García-Melendo and ten others worked on what became their article “Colors of Jupiters large anticyclones and the interaction of a Tropical Red Oval with the Great Red Spot in 2008“. These authors looked specifically at this oddly red oval and how it interacted with the GRS.
Unfortunately, we did not see the formation of the RO because of conjunction (in which a planet farther from the sun than Earth is on the opposite side of the sun from our point of view, and thus cannot be seen). RO was first noted in February 2008. For comparison, they also had BA, a white oval with a reddish ring inside it, which had formed in a merge of three white ovals. The ring within BA was less red than RO, which in turn is a fairly similar shade of red to the GRS. RO also had a dark ring around it, which is not uncommon, and this seemed to act as a barrier to prevent any mixing or dispersion of its color.
A view from the JUNO spacecraft one July 10th, 2016, days after its arrival at the planet Jupiter. Labeled are three of Jupiter's moons. Image credit JPL/NASA.
A view from the JUNO spacecraft one July 10th, 2016, days after its arrival at the planet Jupiter. Labeled are three of Jupiter’s moons. Image credit JPL/NASA.
When it met the west side of the GRS on the 28th of June 2008, RO was moved southward, along the edge of the GRS. It became sandwiched between the GRS and BA, which stretched it. It emerged on the other side of the GRS near the 6th and 7th of July 2008, appearing distorted and less red. After that, it slowly dissipated entirely.
Comparisons between BA, the GRS, and RO indicate that neither strength of vortex, nor circulation, nor the depth of the vortex below the cloud tops determines the color of the oval. This might seem like a useless result, but ruling possibilities out can be helpful; process of elimination. One possibility is that some sort of material, when exposed to ultraviolet light, or through a chemical process not yet entirely known, or a combination of both, produces the red color. This material may or may not be present in all or part of a storm, ergo the color difference between otherwise similar storms. However, we are still not quite sure. Future research (perhaps that done by the Juno spacecraft, which went into orbit around Jupiter on July 4th, 2016) will hopefully be able to shed some light on this.
Bibliography
Bennett, Jeffrey O., ed. The Cosmic Perspective: the Solar System. 7th ed. Boston: Addison-Wesley, 2014. Print.
Textbook used for information on conjunction and background on the Great Red Spot.
Candanosa, Roberto. Hille Karl, ed.  “Jupiter’s Great Red Spot: A Swirling Mystery.”  NASA. N.p., 5 Aug. 2015. Web.
A short article discussing Jupiter and some of its mysteries, including the origin of its colors.
National Aeronautics and Space Administration. “Jupiter: Overview.” Solar System Exploration. N.p., n.d. Web.
The source of the first image, showing Jupiter’s Great Red Spot.
Perez, Martin, ed. “Juno’s Post-Arrival View“. NASA, 12 July 2016. Web.
Another short article discussing Juno’s arrival at Jupiter, and the source for the second image.
Sanchez-Lavega, A., et al. (2013), Colors of Jupiter’s large anticyclones and the interaction of a Tropical Red Oval with the Great Red Spot in 2008, J. Geophys. Res. Planets, 118, 2537–2557, doi:10.1002/2013JE004371.
Today’s main article.
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