Jupiter: Are you ready for your close-up? A collection of images of the gargantuan planet, taken by Hubble, have been amalgamated into a planetary portrait, the first in a series of annual portraits of the gas giant members of the Solar System. Jupiter's famous Great Red Spot, its dramatic cloud cover, and even a new elusive wave-like structure comprised of gas have been documented in incredible detail by NASA.

Collecting annual images of Jupiter, Saturn, Uranus and Neptune will help both current and future scientists observe how these enormous worlds change over time in fine detail, including any alterations to their weather patterns and atmospheric chemistry. Using Hubble’s high-resolution Wide Field Camera 3, two global maps of Jupiter have been produced.

^{Video credit: NASA}

Unfortunately, there’s some bad news: The famous Great Red Spot, that vast anti-cyclone with wind speeds of up to 644 kilometers per hour (400 miles per hour), is shrinking. This isn’t breaking news for planetary scientists – this storm, which can fit three entire planet Earths within its boundaries – has been shrinking for perhaps the last four centuries. In the last 200 years, it has shrunk by over 50%. An unusual wispy structure has also been observed spanning almost the entire width of the Great Red Spot, rotating and distorting itself throughout the 10-hour-long image sequence span taken by Hubble.

“Every time we look at Jupiter, we get tantalizing hints that something really exciting is going on,” Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. “This time is no exception.”

This persistent hurricane – which probably gets its orangey-red color from ammonium hydrosulfide chemically reacting with cosmic rays – is still far older than any terrestrial superstorm, which normally last no longer than a week or so. Jupiter’s atmosphere is mostly comprised of hydrogen and helium, with a liquid ocean of hydrogen surrounding its relatively small rocky, icy core. As there is little solid ground to provide friction for the tumultuous atmosphere, storms and winds can continue unimpeded for centuries at the very least.

Simon’s research team think that the Great Red Spot is shrinking because smaller cyclones and anti-cyclones are feeding into the gigantic hurricane, distorting its vortex and causing a chaotic distribution of its internal energy. These parasitic storms could possibly one day sap enough momentum from the hurricane to cause its disintegration.

Up in Jupiter’s North Equatorial Belt, the existence of a second phenomenon, which was discovered only once decades earlier during the Voyager 2 mission, has been confirmed. This stealthy wave, found within the planet’s atmosphere at a latitude frequented by cyclones and anti-cyclones, appears similar in appearance to atmospheric waves on Earth. These terrestrial waves, so-called “baroclinic” waves, tend to appear when cyclones are beginning to form.

This elusive wave pattern on Jupiter has likely remained hidden for so long because it is often concealed beneath the clouds; when it emerges, wave crests are formed in the upper atmosphere, leaving a trace of its path.

^{A false-color image of the elusive wave pattern, with its wave crests indicated by the white arrows. Image credit: NASA}

“The long-term value of the Outer Planet Atmospheres Legacy program is really exciting,” said co-author Michael H. Wong of the University of California, Berkeley, in the same statement. “The collection of maps that we will build up over time will not only help scientists understand the atmospheres of our giant planets, but also the atmospheres of planets being discovered around other stars, and Earth’s atmosphere and oceans, too.”

Think of the annual planetary portraits as the yearly school photograph for our very own Solar System. Just like a schoolchild being asked to sit still, Jupiter simply refuses.