The Great Red Spot on Jupiter, they were first imaged from the Voyager 1 in 1979. This was the closest view of the Great Red Spot ever received, but the Juno spacecraft will get approximately 20 times closer than Voyager 1 ever did.
Jupiter is the Solar System’s largest planet, with the largest continuously-raging storm ever known.
NASA, ESA, and E. Karkoschka (U. Arizona)
At 317 the mass of Earth, Jupiter is the largest and most massive planet in the solar system, and it also boasts the largest storm: the Great Red Spot, as seen here.
Jupiter’s Great Red Spot (GRS) was discovered in 1665, they are raging continuously from at least 1830 until today.
NASA / Pioneer 10
At earlier times than the late 1970s, Jupiter’s Great Red Spot was in between the large, dark bands, rather than adjacent to one close to the equator. This may explain why the red spot has been shrinking in recent years.
The spot appeared solid and larger in the early 20th century but appeared smaller and more storm-like when Voyager 1 flew past in 1979.
NASA, Caltech / JPL
A false-color image of the Great Red Spot of Jupiter from Voyager 1. The white oval storm directly below the Great Red Spot, a temporary storm that has since dissipated, has approximately the same diameter as the Earth.
At its maximum, the GRS was 40,000 kilometers across: more than three Earth diameters long.
NASA; Brian0918 at English Wikipedia
Jupiter may be approximately 11-12 times the diameter of Earth, but the Great Red Spot has shrunk from a maximum of 40,000 km to merely 24,000 km across, as of 2017.
It’s barely half that extent today; if the shrinking continues, it will be completely circular by 2040.
NASA, ESA, and A. Simon (Goddard Space Flight Center)
Images from the Hubble Space Telescope show the Great Red Spot shrinking in extent and changing in shape even from 1995 (top) to 2009 (middle) to 2014 (bottom).
There are three theories as to why it’s red:
an organic compound,
or a reddish sulfur compound: ammonium hydrosulfide.
NASA/JPL/University of Arizona
The first color movie of Jupiter from NASA’s Cassini spacecraft shows what it would look like to peel the entire globe of Jupiter, stretch it out on a wall into the form of a rectangular map, and watch its atmosphere evolve with time.
Juno, celebrating its one-year anniversary orbiting Jupiter, is equipped with cloud-penetrating instruments to find out.
Simulated images from the Juno mission, just in advance of orbital insertion last year.
The GRS is colder and higher in altitude (by about 8 kilometers) than the rest of Jupiter’s atmosphere.
Art by Karen Teramura, UH IfA with James O’Donoghue and Luke Moore
In theory, the differing properties of Jupiter’s great red spot, distinct from the rest of the atmosphere, could be related to thermal differences coming from below.
Chemical and atmospheric processes occurring below the cloud-tops powers this storm.
With 600+ km/hr winds, this storm is much faster than any winds ever known on Earth.
Zooming in on the Great Red Spot at Blue(left) and red (right) wavelengths reveals a unique filamentary feature that had never been seen before. There is still much to learn about this spot.
Juno observes the Great Red Spot today, just 9,000 kilometers up, with all 8 instruments and its JunoCam imager.
Juno’s mission details are highlighted by eight independent instruments all capable of analyzing its atmospheric properties in a variety of ways, along with its high-resolution imager, Junocam.
With this new data, many mysteries might finally be solved.