One advantage of planetary science is that visions from one planet can explain phenomena on another. We understand Venus“The greenhouse effect is from our own experience on Earth, and Jupiter and Saturn share some characteristics.
But Jupiter also provides insights into other distant systems, such as Uranus and Neptune.
Now, a discovery from a spacecraft orbiting Jupiter may have solved an ancient mystery about Uranus and Neptune – where everything is ammonia Went?
Scientists have long noticed the absence of ammonia in the atmospheres of Uranus and Neptune when compared to the amounts seen on Jupiter and Saturn.
This fact was considered by many to be strange as models of planetary formation suggested that all gas giants originated from the same “primordial soup”, so their compositions should be similar.
Theories abound as to where the ammonia went, but a closer examination of Jupiter himself hints at a possible explanation.
Like hailstones, these fungus balls are more liquid than traditional hailstones, with liquid ammonia coming into contact with water even at extremely low temperatures, such as those in Jupiter’s upper atmosphere.
These fused balls of fungus can grow to be larger than some giant hailstones on Earth. It is also subject to rapid fall into the atmosphere, pulling its component parts downward from the upper reaches of the atmosphere.
As they approach Jupiter’s center, the temperature rises, causing the ammonia and water to evaporate and allow them to rise again toward the observable upper reaches.
According to Tristan Guillot of CRNS Laboratoire Lagrange, the same process may occur on Neptune and Uranus, but the fungus balls keep ammonia in the lower atmosphere longer, with little chance of releasing it back to observable heights.
At such low altitudes, ammonia appears to be missing with current monitoring capabilities. The upper layers of clouds will block any reading of the ammonia, making it look like it has disappeared.
To see the disappearing ammonia would require a mission specifically dedicated to exploring the lower atmospheres of exoplanets. Some missions have been announced in the past, but none are currently in the works.
As Dr. Guillot points out, understanding the exoplanets in our solar system will help us understand the atmospheres of exoplanets outside our solar system. Maybe it’s time to send in a dedicated probe to learn more about our farthest planetary neighbors.