The shocking truth about Jupiter

The planet's Great Red Spot is quickly shrinking, and scientists have discovered some odd realities about this epic storm.

As we reported recently, the Great Red Spot that has become iconic on the surface of Jupiter is quickly shrinking. But an astonishing new discovery by scientists thanks to data and imagery from NASA’s Juno spacecraft suggests we may have much more to learn about this gas giant, and it could help us better understand planet formation in our solar system.

Scientists believe that this gigantic storm, which is so big that it could fit the entire Earth inside of it, is shrinking at a pace that would cause it to disappear within our lifetimes. And now it appears the shape of the storm is changing as well, growing taller into the atmosphere and even changing from its trademark red color to an organish hue.

Scientists think this is happening because of the fact that the gasses fromt he storm are getting pushed higher up in the atmosphere and are interacting with ultraviolet radiation that is being put out by our sun. This extraordinary development will be monitored by Juno and will provide scientists with greater insights on this gas giant.

The paper was published in the Astronomical Journal. The abstract follows below.

Observations of Jupiter’s Great Red Spot (GRS) span more than 150 years. This allows for careful measurements of its size and drift rate. High spatial resolution spacecraft data also allow tracking of its spectral characteristics and internal dynamics and structure. The GRS continues to shrink in longitudinal length at an approximately linear rate of 0fdg194 yr−1 and in latitudinal width at 0fdg048 yr−1. Its westward drift rate (relative to System III W. longitude) has increased from ~0fdg26/day in the 1980s to ~0fdg36/day currently. Since 2014, the GRS’s short wavelength (<650 nm) reflectance has continued to decrease, while it has become brighter at 890 nm, indicating a change in clouds/haze at high altitudes. In addition, its north–south color asymmetry has decreased, and the dark core has become smaller. Internal velocities have increased on its east and west edges, and decreased on the north and south, resulting in decreased relative vorticity and circulation. The GRS’s color changes from 2014 to 2017 may be explained by changes in stretching vorticity or divergence acting to balance the decrease in relative vorticity.

The following is an excerpt from Wikipedia on the Great Red Spot.

The Great Red Spot is a persistent high-pressure region in the atmosphere of Jupiter, producing an anticyclonic storm 22° south of the planet’s equator. It has been continuously observed for 188 years, since 1830.[1] Earlier observations from 1665 to 1713 are believed to be of the same storm; if this is correct, it has existed for at least 350 years.[2][3] Such storms are not uncommon within the turbulent atmospheres of gas giants.

The Great Red Spot may have existed since before 1665, but the present spot was first seen only after 1830 and well-studied only after a prominent apparition in 1879. The storm people had seen in the 1600s may have been a different storm than the one we see today.[4] A long gap separates its period of current study after 1830 from its seventeenth-century discovery; whether the original spot dissipated and reformed, whether it faded, or even if the observational record was simply poor, are all unknown.[5]

For example, its first sighting is often credited to Robert Hooke, who described a spot on the planet in May 1664; however, it is likely that Hooke’s spot was in the wrong belt altogether (the North Equatorial Belt, versus the current Great Red Spot’s location in the South Equatorial Belt). Much more convincing is Giovanni Cassini’s description of a “permanent spot” the following year.[6] With fluctuations in visibility, Cassini’s spot was observed from 1665 to 1713; however, the 118-year observational gap makes the identity of the two spots inconclusive, and the older spot’s shorter observational history and slower motion than the modern spot make their identity unlikely.[7]

A minor mystery concerns a Jovian spot depicted in a 1711 canvas by Donato Creti, which is exhibited in the Vatican.[8][9] Part of a series of panels in which different (magnified) heavenly bodies serve as backdrops for various Italian scenes, and all overseen by the astronomer Eustachio Manfredi for accuracy, Creti’s painting is the first known to depict the Great Red Spot as red. No Jovian feature was explicitly described as red before the late 1800s.

The oval object rotates counter-clockwise, with a period of about six Earth days or fourteen Jovian days. Measuring in at 10,159 miles (16,350 kilometers) in width (as of April 3, 2017) Jupiter’s Great Red Spot is 1.3 times as wide as Earth. The cloud-tops of this storm are about eight kilometres above the surrounding cloud-tops.

Infrared data have long indicated that the Great Red Spot is colder (and thus, higher in altitude) than most of the other clouds on the planet. However, recent infrared measurements of the upper atmosphere show far more heat above the Great Red Spot than the rest of the planet; “acoustic waves” rising from the storm have been proposed as an explanation for Jupiter’s temperature.

Careful tracking of atmospheric features revealed the spot’s counter-clockwise circulation as far back as 1966, observations dramatically confirmed by the first time-lapse movies from the Voyager fly-bys. The spot is confined by a modest eastward jet stream to its south and a very strong westward one to its north. Though winds around the edge of the spot peak at ~120 metres per second (432 kilometres per hour), currents inside it seem stagnant, with little inflow or outflow. The rotation period of the spot has decreased with time, perhaps as a direct result of its steady reduction in size.

The Great Red Spot’s latitude has been stable for the duration of good observational records, typically varying by about a degree. Its longitude, however, is subject to constant variation.[27][28] Because Jupiter does not rotate uniformly at all latitudes, astronomers have defined three different systems for defining the longitude. System II is used for latitudes of more than 10°, and was originally based on the average rotation rate of the Great Red Spot of 9h 55m 42s. Despite this, however, the spot has “lapped” the planet in System II at least 10 times since the early nineteenth century. Its drift rate has changed dramatically over the years and has been linked to the brightness of the South Equatorial Belt, and the presence or absence of a South Tropical Disturbance.

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