Giant 'Mushballs' Could Be Hiding The Missing Ammonia on Neptune And Uranus

The beauty of planetary science is the possibility that information from one planet can explain phenomena on another. From our experience on the Earth, we understand Venus' greenhouse gas effects. Jupiter and Saturn share certain characteristics.
Jupiter can also provide insight into distant systems like Uranus or Neptune.

A spacecraft orbiting Jupiter may have made a breakthrough that could solve a long-standing mystery regarding Uranus and Neptune. Where has all the ammonia gone, this discovery might help.

Scientists have noticed a lack of ammonia in Uranus and Neptune's atmospheres, compared to Jupiter and Saturn.

Many thought that this was strange, as the planetary formation models suggested all gas giants were derived from the same "primordial soup," so their compositions should also be similar.

There are many theories about where the ammonia went, but Jupiter's close inspection suggests a possible explanation.

Juno, a probe currently exploring Jupiter's system, observed that ammonia in upper atmosphere created "mushballs" when it merged with water.

These mushballs look a lot like hailstones. The ammonia liquefies water when it comes in contact with it, even at very low temperatures such as those found in Jupiter’s upper atmosphere.

These mashballs can be larger than the hailstones. They can also fall rapidly through the atmosphere, dragging the parts they are made out of the upper reaches.

They get closer to Jupiter's center, and the temperature rises. This vaporizes ammonia and water, and allows them to climb back up to the upper observable reaches.

(NASA /JPL-Caltech/SwRI /CNRS)

Tristan Guillot, CRNS Laboratoire Lagrange says that the same thing might be occurring on Neptune or Uranus. However, the mushballs keep the ammonia in the lower atmosphere longer and have less chance of releasing it up to higher altitudes.

The ammonia at such low altitudes would seem to be absent from current observations. Any ammonia readings would be obscured by the clouds, giving it the appearance of disappearing.

A dedicated mission to the outer planets' lower atmospheres would be required in order to see the ammonia gone. While there have been some missions in the past that were mentioned, none of them are currently operational.

Dr. Guillot argues that understanding the outer planets within our solar system would allow us to understand the atmospheres of exoplanets beyond our solar system. It might be time to send a dedicated probe to investigate our distant planetary neighbors.

Universe Today originally published this article. You can read the original article.

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