Ammonia sparks unexpected, exotic lightning on Jupiter

August 05, 2020

ITHACA, N.Y. - NASA's Juno spacecraft - orbiting and closely observing the planet Jupiter - has unexpectedly discovered lightning in the planet's upper atmosphere, according to a multi-institutional study led by the NASA/Jet Propulsion Laboratory (JPL), which includes two Cornell University researchers.

The work was published Aug. 5 in the journal Nature.

Jupiter's gaseous atmosphere seems placid from a distance, but up close the clouds roil in a turbulent, chemically dynamic realm. As scientists have probed the opaque surface with Juno's sensitive instrumentation, they've learned that Jupiter's lightning occurs not only deep within the water clouds but also in shallow atmospheric regions (at high altitudes with lower pressure) that feature clouds of ammonia mixed with water.

"On the night side of Jupiter, you see fairly frequent flashes - as if you were above an active thunderstorm on Earth," said Jonathan I. Lunine, the David C. Duncan Professor in the Physical Sciences and chair of the Department of Astronomy in the College of Arts and Sciences at Cornell University. "You get these tall columns and anvils of clouds, and the lightning is going continuously. We can get some pretty substantial lightning here on Earth, and the same is true for Jupiter."

The research, "Small Lightning Flashes From Shallow Electrical Storms on Jupiter," was directed by Heidi N. Becker, the Radiation Monitoring Investigation lead of NASA's Juno mission. Lunine and doctoral candidate Youry Aglyamov were the two Cornell co-authors in the study.

Previous missions to Jupiter - such as Voyager 1, Galileo and New Horizons - had all observed lightning. But thanks to Juno's Stellar Reference Unit, a camera designed to detect dim sources of light, the spacecraft's close observational distance and instrument sensitivity enabled lightning detection at a higher resolution than previously possible.

Ammonia is the key. While there is water and other chemical elements such as molecular hydrogen and helium in Jupiter's clouds, ammonia is the "antifreeze" that keeps water in those upper atmospheric clouds from freezing entirely.

Lunine notes Aglyamov's ongoing dissertation work focuses on how lightning is generated under these conditions. The collision of the falling droplets of mixed ammonia and water with suspended water-ice particles constitutes a way to separate charge and produce cloud electrification - resulting in lightning storms in the upper atmosphere.

"The shallow lightning really points to the role of ammonia, and Youry's models are starting to confirm this," Lunine said. "This would be unlike any process that occurs on Earth."

Jupiter's wild gaseous world fascinates Aglyamov.

"Giant planets in general are a fundamentally different kind of world from Earth and other terrestrial planets," he said. "There are hydrogen seas transitioning gradually into skies stacked with cloud decks, weather systems the size of the Earth and who-knows-what in the interior."

The discovery of shallow lightning on Jupiter shifts our understanding of the planet, Aglyamov said.

"Shallow lightning hadn't really been expected and indicates that there's an unexpected process causing it," he said. "It's one more way in which Juno's observations show a much more complex atmosphere of Jupiter than had been predicted. We know enough now to ask the right questions about processes going on there, but as Juno shows, we're in a stage where every answer also tends to multiply the questions."
-end-
Funding for the Cornell portion of this research comes from the Southwest Research Institute.

Cornell University

Related Atmosphere Articles from Brightsurf:

ALMA shows volcanic impact on Io's atmosphere
New radio images from ALMA show for the first time the direct effect of volcanic activity on the atmosphere of Jupiter's moon Io.

New study detects ringing of the global atmosphere
A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai'i at Mānoa, shows that the Earth's entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries.

Estuaries are warming at twice the rate of oceans and atmosphere
A 12-year study of 166 estuaries in south-east Australia shows that the waters of lakes, creeks, rivers and lagoons increased 2.16 degrees in temperature and increased acidity.

What makes Saturn's atmosphere so hot
New analysis of data from NASA's Cassini spacecraft found that electric currents, triggered by interactions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the planet's upper atmosphere.

Galactic cosmic rays affect Titan's atmosphere
Planetary scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) revealed the secrets of the atmosphere of Titan, the largest moon of Saturn.

Physics: An ultrafast glimpse of the photochemistry of the atmosphere
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

Using lasers to visualize molecular mysteries in our atmosphere
Molecular interactions between gases and liquids underpin much of our lives, but difficulties in measuring gas-liquid collisions have so far prevented the fundamental exploration of these processes.

The atmosphere of a new ultra hot Jupiter is analyzed
The combination of observations made with the CARMENES spectrograph on the 3.5m telescope at Calar Alto Observatory (Almería), and the HARPS-N spectrograph on the National Galileo Telescope (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma) has enabled a team from the Instituto de Astrofísica de Canarias (IAC) and from the University of La Laguna (ULL) to reveal new details about this extrasolar planet, which has a surface temperature of around 2000 K.

An exoplanet loses its atmosphere in the form of a tail
A new study, led by scientists from the Instituto de Astrofísica de Canarias (IAC), reveals that the giant exoplanet WASP-69b carries a comet-like tail made up of helium particles escaping from its gravitational field propelled by the ultraviolet radiation of its star.

Iron and titanium in the atmosphere of an exoplanet
Exoplanets can orbit close to their host star. When the host star is much hotter than our sun, then the exoplanet becomes as hot as a star.

Read More: Atmosphere News and Atmosphere Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.