As we have seen, Jupiter has long been the Solar System giant planet with a fast spin and bands and the physics of which is familiar and scaled to enormous size. However, the more closely scientists examine it the more the planet insists on not fitting into the neat frames of textbook expectations. Patterns of temperature alternate in baffling symmetry between the hemispheres, chemical substances are found in the wrong place, and polar light burst forth in a strength that is not explained by terrestrial experience.
Thermal behavior is one of the most enduring surprises that appear nearly artificial. Several decades of observations with infrared have shown that the upper atmosphere of Jupiter can heat up in one hemisphere and cool in the other, a near mirror image effect that can hardly be explained as simple seasonal forcing on a planet with a very small axial gradient. The outcome is not just an interest of weather graphs; it is an indication that there is energy and momentum being shuffled about the earth via channels which are not entirely reflected in conventional models.
The measurements of the gravity of Juno bring to the puzzle an important bit of information, because it brings out the relation of the visible bands and the interior that is unseen. Rather than becoming faded away in a downward direction as the pattern of a surface upon a rotating ball, the prominent east-west winds of Jupiter seem to become drawn inwards in the form of cylindrical layers at right angles to the spinning axis. The same data set also shows that the belts and zones go down to an approximate of 1,860 miles (3,000 kilometers) below the cloud tops, so down that the line between “atmosphere” and “interior” is obliterated. Monitoring the radio signal of the spacecraft on close flybys – sensitive to any change in velocity as minute as 0.01 millimeter per second – allows scientists to understand the distribution of mass, and thus to deduce the structure of the winds beneath the clouds.
The importance of such a deep structure is that it does not just stir the cloud deck seen on the surface, but it seems that the chemistry of the planet is also being sorted by Jupiter. Violent convection is increasingly the focus of observations and modeling as the elevation of ammonia and water to sufficient altitude to freeze in the form of slushy hailstones, or “mushballs”. These falling particles may then drag ammonia downwards, a process that can be used to explain why some parts of the gas giant are strangely ammonia deficient relative to what an unlayered gas giant should appear like.
Even the most iconic of the storms of Jupiter is not standing still. The Great Red Spot which used to be approximately 25,500 miles long along its well-known axis in the late nineteenth century has shrunk drastically; Hubble discovery records it to be approximately 10,250 miles wide in more modern measurements. Recent Hubble Space Telescope findings reveal that now the Great Red Spot (GRS) is about 10,250 miles in diameter, the smallest we ever measured. An increased rate of shrinkage an increase of approximately 580 miles per year and a change in shape, no longer oval but more circular, has also been recorded and this suggests that the vortex is having its energy storage and energy loss mechanisms changed by small eddies pouring into it.
Another diagnosis is given by auroras, which relate the upper atmosphere of Jupiter with its vast magnetic environment. The birth of the auroral storms of the night side has been photographed by the ultraviolet apparatus of Juno, before the brightening turns in sight. They have the potential of emitting hundreds to thousands of gigawatts of ultraviolet energy and leaving at least 10 times the amount of energy in the upper atmosphere than normal aurora does. The process is not merely an extension of the auras playbook of the Earth, partly due to the fact that the magnetosphere of Jupiter is overloaded with particles furnished by Io, which are imprisoned and accelerated by the Jovian magnetic field.
Meanwhile, attempts to create a chemistry to match the dynamics of Jupiter are increasingly becoming computationally ambitious. A more elaborate atmospheric model, combining chemistry and fluid motion, estimates that the planet has 1.5 times the oxygen of the Sun, and that vertical mixing is often much slower than often guessed, as much as 35 or 40 times slower, by which the time needed to transport molecules up and down the layers can range between a few hours and a few weeks. Those findings bring into closer relation to each other what telescopes observe in the upper atmosphere and what must be going on far down below where pressure and temperature are pushing ordinary matter into strange regimes.
Through storms and winds and auroras and chemistry, Jupiter becomes more and more uniform in a single feature: the planet is not a superposition of distinct layers, but a complex interrelationship. Jupiter is not simplified by Juno and long-baseline observations; it has been made legible enough to demonstrate where the old simplifications fail.
