New maps of Jupiter offer plenty of surprises

This new image from the largest planet in the Solar System, Jupiter, was made during the Outer Planet Atmospheres Legacy (OPAL) program. The images from this program make it possible to determine the speeds of Jupiter's winds, to identify different phenomena in its atmosphere and to track changes in its most famous features. (ESA)

In a given year, Jupiter experiences its share of storms, cloudy days and changes in atmospheric chemistry.

Now, scientists have brought all that together in new maps that reveal the planet in a new and surprising light. Already, the images have exposed a rare wave just north of the planet’s equator and a unique filamentary feature in the core of the Great Red Spot not seen previously.

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“Every time we look at Jupiter, we get tantalizing hints that something really exciting is going on,” said Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, whose findings were described in an Astrophysical Journal paper, in a press release.  “This time is no exception.”

The maps are giving scientists a longer-term view of the planet. It is the first in a series of annual portraits of the solar system’s outer planets.

Simon and her colleagues produced two global maps of Jupiter from observations made using the Hubble space telescope's high-performance Wide Field Camera 3. The two maps represent nearly back-to-back rotations of the planet, making it possible to determine the speeds of Jupiter’s winds.

The new images also confirm that the Great Red Spot continues to shrink and become more circular, as it has been doing for years. The long axis of this characteristic storm is about 150 miles shorter now than it was in 2014.

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The Great Red Spot appears more orange than red, and its core, which typically has more intense color, is less distinct than it used to be. An unusual wispy filament can also be seen, spanning almost the entire width of the vortex. This filamentary streamer rotates and twists throughout the 10-hour span of the Great Red Spot image sequence, getting distorted by winds blowing at 330 miles per hour or even greater speeds.

In Jupiter’s North Equatorial Belt, the researchers found an elusive wave that had been spotted on the planet only once before, decades earlier, by Voyager 2. In those images, the wave is barely visible, and nothing like it was seen again, until the current wave was found traveling at about 16 degrees north latitude, in a region dotted with cyclones and anticyclones.

Similar waves -- called baroclinic waves -- sometimes appear in Earth’s atmosphere where cyclones are forming.

“Until now, we thought the wave seen by Voyager 2 might have been a fluke,” said co-author Glenn Orton of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in the press release. “As it turns out, it’s just rare!”

The wave may originate in a clear layer beneath the clouds, only becoming visible when it propagates up into the cloud deck, according to the researchers.

After Jupiter, researchers plan to release maps of Neptune and Uranus. Saturn will be added to the series later.

“The long-term value of the Outer Planet Atmospheres Legacy program is really exciting,” said co-author Michael Wong of the University of California, Berkeley, in the press release. “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.”