Spying Deep Inside the Storms of Jupiter

The Cosmic Companion
Aug 24 · 5 min read

Storms on Jupiter are immensely powerful events, and they have been studied and photographed for decades. But, now, new observations from the Atacama Large Millimeter Array (ALMA) radio telescope network have been combined with observations from some of the most powerful telescopes in (and above) the Earth, allowing astronomers to look deep beneath the clouds, revealing secrets of these terrible tempests.

Radio waves offer astronomers a chance to peek beneath the opaque haze of the atmosphere of Jupiter. Poking through the haze, these frequencies reveal movement taking place beneath the familiar cloud tops of Jupiter, showing the largest planet of the Solar System in a new light.

The Great Red Spot on Jupiter, seen in radio waves by the Very Large Array, and the Hubble Space Telescope (below). Image credit: de Pater, et al., NRAO/AUI/NSF; NASA

“ALMA enabled us to make a three-dimensional map of the distribution of ammonia gas below the clouds. And for the first time, we were able to study the atmosphere below the ammonia cloud layers after an energetic eruption on Jupiter,” said Imke de Pater of the University of California, Berkeley.

Don’t Think About What it Must Smell Like…

The atmosphere of Jupiter is composed of hydrogen, helium, and small amounts of methane, ammonia, hydrogen sulfide, and water, while the top-most layer of the Jovian atmosphere is mostly ammonia ice. Just under the top layer sits a region of ammonium hydrosulfide particles. Roughly 80 kilometers (50 miles) beneath the outermost gases, clouds of liquid water are thought to encircle this massive world.

Movement within these three layers create the distinctive stripes of tan, brown, and white that make up the familiar markings of Jupiter.

Magnificent storms form within the upper three layers of the Jovian atmosphere. These events, often associated with lightning, are seen in visible light as white plumes in the atmosphere of the planet. The effects of these storms can still be seen in the patterns of Jupiter for months or years following such a tempest.

“…and then, in dreaming, The clouds methought would open and show riches ready to drop upon me, that when I waked, I cried to dream again.”
― William Shakespeare, The Tempest

I’ve Seen the Clouds from Both Sides Now…

Searching 100 kilometers (63 miles) beneath the surface of the visible shroud of Jupiter, researchers at the Very Large Array (VLA) revealed motions of the upper atmosphere.

“This region was previously unexplored. These observations give us important new information about the temperatures, pressures, and motions of gas at these levels of the atmosphere,” de Pater states.

The ammonia clouds of Jupiter seen under the cloud tops of Jupiter by the ALMA Observatory. Image credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello

Networks of radio telescopes like ALMA, require targets to be exposed for long periods of time. Such a study of Jupiter, which rotates once every 10 hours, would smudge the data. A data-reduction technique was used to “unsmudge” the several-hour-long exposure.

Astronomers long believed the stripes of Jupiter were related to features seen in radio wavelengths. However, these new readings from the VLA show radio events that seem to be independent of any visible marking.

Gas seen rising through the upper layers of the Jovian atmosphere could predecessors to future storms, researchers suggest. Rising gases in the Jovian atmosphere even appear to change the color of the bands of the mighty planet.

The moist convection theory of Jovian storms holds that the transfer of heat in the atmosphere of Jupiter pushes ammonia and water vapor up to 80 kilometers (50 miles) from the outermost layers of the atmosphere. Once there, water is thought to condense into droplets. Heat released from this transition warms the cloud, which in turn, expands. This lifts the updraft higher, beyond the outer reaches of the clouds of ammonia gas in the outermost layer of the gas giant. When this ammonia touches space and freezes, it turns white, forming the plumes seen from Earth.

The moist convection process postulated to explain the white plumes of Jupiter, and their effects on local bands of color. Adapted from illustration by Leigh Fletcher, University of Leicester.

“If these plumes are vigorous and continue to have convective events, they may disturb one of these entire bands over time, though it may take a few months. With these observations, we see one plume in progress and the aftereffects of the others.” de Pater explains.

In January 2017, Australian amateur astronomer Phil Miles announced his detection of an eruption in Jupiter’s South Equatorial Belt. First seen as a tiny, white plume, the storm created a disruption in its home belt which was visible to astronomers for several weeks.

I’m Totally on Your Wavelength

Within days, professional astronomers set the sights of the ALMA Observatory toward the massive storm. The eyes of ALMA, searching the region in radio frequencies, was able to peer beneath the outer curtains of the most massive world in the Solar System.

“Jupiter was observed with ALMA on 3–5 January 2017, when the array was composed of 40 antennas, and placed in a relatively compact configuration,” researchers report in Astronomical Journal.

Scenes of the event were collected by six instruments, including the Hubble Space Telescope (HST). When the HST turned its eye to the region, the spaceborne observatory spotted s second, similar plume. Astronomers postulate this second plume was the result of the same conditions that formed the original target.

The ALMA images were compared to data collected by other observatories in the infrared and visible/ultraviolet wavelengths of the electromagnetic spectrum.

The site of the eruption on Jupiter, seen in radio images from ALMA (above) and the Hubble Space Telescope (below). Image credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA/Hubble

“Our ALMA observations are the first to show that high concentrations of ammonia gas are brought up during an energetic eruption. The combination of observations simultaneously at many different wavelengths enabled us to examine the eruption in detail,” de Pater stated.

By looking at targets in various wavelengths, astronomers are able to study a wide range of celestial events and detail conditions on distant bodies. Comparing and merging data from observations taken in different wavelengths can reveal processes happening on targets, unseen in single snapshots.

The Great Red Spot of Jupiter, seen in optical and radio wavelengths. Image credit: NRAO/AUI/NSF

These ALMA observations, together with the data collected in other frequencies, revealed the presence of ammonia, rising through the upper layers of the atmosphere. Plumes of the gas rose high above the main ammonia deck, the study reveals.

Just two to three months before ALMA trained its sights on this storm, a similar tempest was seen in the northern hemisphere of the planetary giant.

Jupiter holds on to approximately 75 percent of all the matter in the Solar System, other than the Sun. The other gas giant in our planetary family, Saturn, is home to an additional 15 percent of the total. Earth and the other six planets in our family of worlds, combined, holds on to just 10 percent of the non-solar mass of the Solar System.

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The Cosmic Companion

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Written by

James Maynard is the author of two books, and thousands of articles about space and science. E-mail: thecosmiccompanion@gmail.com

The Cosmic Companion

Exploring the wonders of the Cosmos, one mystery at a time

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