Juno Looks Into The Eye Of The Storm

Jupiter’s Great Red Spot has been a swirling mystery for centuries–an enormous wildly whirling storm that has lingered in its planet’s sky for the past 150 years–or longer. While stargazers on Earth saw a huge strange spot, staining the top layer of Jupiter’s clouds as early as the 1600s–which is when observers first started using primitive telescopes–it is still not clear if they were observing a different storm, rather than the Great Red Spot we now see. Today, astronomers realize that Jupiter’s Great Red Spot is really there, and that it has been there for a long time, but they still struggle to understand what causes its wild whirl of crimson hues. In July 2017, images of Jupiter’s crimson storm were obtained that unveil a complex tangle of dark venous clouds weaving their weird way through a massive red oval. The JunoCam imager aboard NASA’s Juno mission spacecraft snapped revealing pictures of the most iconic feature of the Solar System’s largest planetary denizen during its July 10, 2017 flyby above the giant planet. The newly obtained images of the mysterious swirling spot were promptly downlinked from the spacecraft’s memory on July 11, 2017 and then placed on the mission’s JunoCam website on the morning of July 12.

“For hundreds of years scientists have been observing, wondering and theorizing about Jupiter’s Great Red Spot. Now that we have the best pictures ever of this iconic storm. it will take us some time to analyze all the data from not only JunoCam, but Juno’s eight science instruments, to shed some new light on the past, present, and future of the Great Spot,” commented Dr. Scott Bolton in a July 12, 2017 NASA Jet Propulsion Laboratory (JPL) Press Release. Dr. Bolton is Juno principal investigator from the Southwest Research Institute in San Antonio, Texas. The JPL is in Pasadena, California.

As planned by the Juno team, citizen scientists obtained the raw images of the flyby from the JunoCam site and then processed them. As a result, the images now provide a higher level of detail than when they are in their raw form.

“I have been following the Juno mission since it was launched. It is always exciting to see these new raw images of Jupiter as they arrive. But it is even more thrilling to take the raw images and turn them into something that people can appreciate. That is what I live for,” commented Jason Major in the July 12, 2017 NASA Jet Propulsion Laboratory Press Release. Major is a JunoCam citizen scientist and a graphic designer from Warwick, Rhode Island.

Gaining a scientific understanding of the Great Red Spot has not been easy–and this is Jupiter’s own fault. This banded behemoth gas-giant is a thousand times bigger than Earth, and it is composed primarily of gas. However, many planetary scientists think that a liquid ocean of hydrogen encircles Jupiter’s well-hidden core, and its atmosphere is composed primarily of hydrogen and helium. This means that there is no solid ground on this enormous world, like we have on Earth, to weaken its fierce storms. In addition, Jupiter’s clouds block clear observations of its lower atmosphere. While some investigations of Jupiter have managed to observe several regions of its lower atmosphere, telescopes and orbiting probes studying the Great Red Spot can only peer at clouds scattered high in the Jovian atmosphere.

Learning more about Jupiter and its swirling red storm can help scientists gain a better understanding of our own planet’s weather, according to Dr. Amy Simon, an expert in planetary atmospheres at NASA’s Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. Jupiter’s weather is subject to the same physics as Earth’s weather–but it is millions of miles farther from our Sun. Furthermore, studies of Jupiter can shed new light on the weather of alien worlds circling stars beyond our Solar System. “If you just look at reflected light from an extrasolar planet, you’re not going to be able to tell what it’s made of. Looking at as many possible different cases in our own Solar System could enable us to then apply that knowledge to extrasolar planets,” Dr. Simon continued to explain in an August 6, 2015 NASA Press Release.

Many studies predict that the Jovian upper atmosphere possesses clouds consisting of water, ammonia, and ammonium hydrosulfide. However, planetary scientists still do not know precisely how or even if these chemicals react to give crimson hues like those observed in the Great Red Spot. Furthermore, these compounds account for only a small part of the Jovian atmosphere. “We’re talking about something that only makes up a really tiny portion of the atmosphere. That’s what makes it so hard to figure out exactly what makes the colors that we see,” Dr. Simon continued to explain.

The Mysterious Realm Of The Banded Behemoth

Jupiter is approximately 89,000 miles wide at its equator, and it is so enormous that all of the other planets inhabiting our Sun’s family could fit inside of it. Indeed, 1,000 Earth’s could be contained within this gaseous banded behemoth world.

Jupiter shares its composition with the stars–and if it had been born approximately 80 times more massive, the process of nuclear fusion would have ignited its stellar furnace, and it would have become a star instead of a planet. If this had occurred, we probably would not be here, trying to understand the secret of the swirling red storm on this distant world.

Jupiter is the fifth planet from our Sun, and its mean distance from it is approximately 5.2 astronomical units (AU). One AU is equal to the average distance between our own planet and the Sun, which is about 93,000,000 miles. This means that Jupiter orbits our Star a little more than five times the distance between Earth and Sun. When Jupiter is observed from Earth, it is usually the second brightest planet in the sky at night–after Venus.

Jupiter rotates faster than any other planet in our Star’s family, and one day on Jupiter is only about 10-hours in duration The Jovian orbit is also elliptical–meaning that it is out of round. One day amounts to one rotation–or spin–of a planet. This colorfully banded giant is also about as big as a giant planet can be, and still be a planet. Jupiter is approximately 90% hydrogen and 10% helium–just like our Sun. However, Jupiter also contains relatively puny amounts of rocky material, methane, ammonia, and water. If any more material had been snared by this enormous planet, it would have been squeezed tightly by the relentless hug of its own gravity–while the entire radius would have increased by only a small amount. Stars can grow to be considerably bigger than Jupiter, and they also possess their own internal source of searing, roasting heat.

When our Solar System came into being about 4.56 billion years ago, it emerged from a very dense, relatively small blob, that was embedded within the billowing, undulating folds of one of the many cold, dark, giant molecular clouds that haunt our Milky Way Galaxy. These enormous, beautiful clouds–composed mostly of gas with only a pinch of dust–serve as the strange nurseries of brilliant newborn stars. As the dense, relatively small blob collapses, most of its material gathers at the center and then ignites as the result of nuclear fusion–and a new star is born. The left over material whirls around the flaming baby protostar, and evolves into what is termed a protoplanetary accreton disk. This rotating disk of gas and dust revolves around the new star–and just such a disk surrounded our primeval Sun. Ultimately the very small particles of “sticky” dust within the disk collide and merge, “gluing” themselves to one another, forming ever larger and larger objects. Eventually, an enormous population of planetesimals form. Planetesimals are planetary building-blocks, from which fully grown planets eventually emerge.

The newborn Jupiter had the potential to become a star–but it failed. The energy emitted by the showering material caused Jupiter’s interior to become searing-hot–and the bigger Jupiter grew, the hotter it became. Eventually, when the material stolen from the ambient, turbulent disk had been devoured, Jupiter might well have displayed an enormous diameter of more than 10 times that which it now has. It is also thought that Jupiter possessed a toasty central temperature of approximately 50,000 degrees Kelvin (the Kelvin scale is an absolute scale of temperature, in which zero equals -459.4), and a brilliant sparkling luminosity that was about 1% as great as that of our fiery Star today.

Many planetary scientists propose, that beneath Jupiter’s clouds, there is a colorless ammonium hydrosulfide layer that could be reacting with cosmic rays or UV radiation from our Star, thus producing the Red Spot’s color. However, there are many other chemicals that turn red under various situations. For the Great Red Spot, as well as other crimson regions of Jupiter, coloring may be the result of many different conditions, as opposed to only ammonium hydrosulfide.

The Great Red Spot is generally considered to be Jupiter’s most prominent feature, as it wildly whirls in the surface layer of Jupiter’s colorfully banded atmosphere. It is a twirling anti-cyclonic storm that is larger than Earth.

Juno Looks Into The Eye Of The Storm

Measuring in at 10,159 miles in width, Jupiter’s Great Red Spot is about 1.3 times as wide as our planet. The swirling crimson storm has been recorded since 1830 and may well have been in existence for over 350 years. In more recent times, the Great Red Spot appeared to be shrinking.

All of the Juno mission’s science instruments and the spacecraft’s JunoCam were operating during the flyby, gathering important data that were then returned to Earth. Juno’s next flybyof Jupiter is scheduled for September 1, 2017.

Juno reached the point at which its orbit came closest to Jupiter’s center (perijove) on July 10, 2017 at 9:55 p.m. EDT, and at the time of perijove Juno was about 2,200 miles above the planet’s cloud tops. Eleven minutes and 33 seconds later, Juno had covered yet another 24,713 miles, and was passing directly above the crimson, coiling, swirling cloud tops of the Great Red Spot. The spacecraft swept about 5,600 miles above the red clouds of this mysterious storm.

Juno launched on August 5, 2011, from Cape Canaveral, Florida. During its mission of exploration, Juno will fly low over the Jovian cloud tops–as close as about 2,100 miles. During these flybys, Juno will be peering beneath Jupiter’s obscuring veil of cloud cover and observing its auroras in order to learn more about the enormous planet’s origins, atmosphere, magnetosphere, and structure.

Early science results derived from Juno show that this banded behemoth is an active and turbulent world, with a fascinating and mysteriously complex interior structure, enormous polar cyclones, and energetic polar aurora.

“These highly anticipated images of Jupiter’s Great Red Spot are the ‘perfect storm’ of art and science. With data from Voyager, Galileo, New Horizons, Hubble and now Juno, we have a better understanding of the composition and evolution of this iconic feature. We are pleased to share the beauty and excitement of space science with everyone,” said Dr. Jim Green in the July 12, 2017 JPL Press Release. Dr. Green is NASA’s durector of planetary science.