Ammonia sparks unexpected, unique lightning on Jupiter

NASA’s Juno spacecraft – orbiting and intently observing the planet Jupiter – has unexpectedly discovered lightning in the planet’s upper atmosphere, according to a multi-institutional analyze led by the NASA/Jet Propulsion Laboratory (JPL), which contains two Cornell scientists.

The function was released Aug. 5 in the journal Nature.

Jupiter’s gaseous atmosphere seems placid from a length, but up shut the clouds roil in a turbulent, chemically dynamic realm. As researchers have probed the opaque area with Juno’s sensitive instrumentation, they’ve learned that Jupiter’s lightning happens not only deep in just the drinking water clouds but also in shallow atmospheric locations (at superior altitudes with decrease strain) that feature clouds of ammonia mixed with drinking water.

“On the evening side of Jupiter, you see rather regular flashes – as if you had been above an energetic thunderstorm on Earth,” stated Jonathan I. Lunine, the David C. Duncan Professor in the Actual physical Sciences and chair of the Section of Astronomy in the School of Arts and Sciences. “You get these tall columns and anvils of clouds, and the lightning is likely consistently. We can get some very significant lightning below on Earth, and the very same is accurate for Jupiter.”

The investigation, “Small Lightning Flashes From Shallow Electrical Storms on Jupiter,” was directed by Heidi N. Becker, the Radiation Checking Investigation guide of NASA’s Juno mission. Lunine and doctoral candidate Youry Aglyamov, M.S. ’20, were being the two Cornell co-authors in the review.

Earlier missions to Jupiter – these as Voyager 1, Galileo and New Horizons – had all observed lightning. But thanks to Juno’s Stellar Reference Device, a camera created to detect dim sources of gentle, the spacecraft’s shut observational length and instrument sensitivity enabled lightning detection at a greater resolution than formerly achievable.

Ammonia is the essential. Though there is h2o and other chemical factors these kinds of as molecular hydrogen and helium in Jupiter’s clouds, ammonia is the “antifreeze” that retains h2o in those people higher atmospheric clouds from freezing entirely.

Lunine notes Aglyamov’s ongoing dissertation do the job focuses on how lightning is generated below these conditions. The collision of the slipping droplets of blended ammonia and drinking water with suspended h2o-ice particles constitutes a way to different charge and develop cloud electrification – resulting in lightning storms in the upper atmosphere.

“The shallow lightning seriously factors to the part of ammonia, and Youry’s designs are starting up to validate this,” Lunine claimed. “This would be in contrast to any approach that occurs on Earth.”

Jupiter’s wild gaseous world fascinates Aglyamov.

“Giant planets in normal are a essentially diverse kind of planet from Earth and other terrestrial planets,” he mentioned. “There are hydrogen seas transitioning steadily into skies stacked with cloud decks, temperature techniques the dimension of the Earth and who-appreciates-what in the interior.”

The discovery of shallow lightning on Jupiter shifts our comprehension of the earth, Aglyamov stated.

“Shallow lightning hadn’t really been expected and implies that there is an unanticipated method triggering it,” he said. “It’s one much more way in which Juno’s observations display a considerably a lot more intricate atmosphere of Jupiter than had been predicted. We know ample now to talk to the appropriate thoughts about processes heading on there, but as Juno reveals, we’re in a phase exactly where every reply also tends to multiply the concerns.”

Funding for the Cornell part of this investigation arrives from the Southwest Exploration Institute.