On Jupiter, it’s mushballs all the way down

April 22, 2025

Imagine a SlusheeTM composed of ammonia and water encased in a hard shell of water ice. Now picture these ice-encrusted slushballs, dubbed “mushballs,” raining down like hailstones during a thunderstorm, illuminated by intense flashes of lightning.

Planetary scientists at the University of California, Berkeley, now say that hailstorms of mushballs accompanied by fierce lightning actually exist on Jupiter. In fact, mushball hailstorms may occur on all gaseous planets in the galaxy, including our solar system’s other giant planets, Saturn, Uranus and Neptune.

The idea of mushballs was initially put forth in 2020 to explain nonuniformities in the distribution of ammonia gas in Jupiter’s upper atmosphere that were detected both by NASA’s Juno mission and by radio telescopes on Earth.

At the time, UC Berkeley graduate student Chris Moeckel and his adviser, Imke de Pater, professor emerita of astronomy and of earth and planetary science, thought the theory too elaborate to be real, requiring highly specific atmospheric conditions.

UC Berkeley News