Uranus and Neptune are the outermost planets of the Solar System and are known as ice giants because they are rich in water. Scientists understand very little about these distant realms. But after the Voyager 2 spacecraft flew by in the 1980s, scientists realized that these worlds occasionally host massive, short-lived storms.
Violent but rare storms occur every few years and are so large that you can see them (with a telescope) from Earth.
Researchers have long wondered why storms on these planets are so unpredictable. Now, a team of astronomers has proposed that methane may hold the key to controlling these storms.
For , heat must rise from a planet’s warm interior to its surface.
There, the heated gas begins to cool, which can cause turbulence and trigger storm formation. But the interiors of these planets are always warm and the outer surfaces are always cold, so why don’t storms happen all the time?
Storms on these planets are unpredictable
In a paper published on the arXiv preprint database, the team pointed out that methane is the third most abundant molecule, after hydrogen and helium, in the deep atmospheres of both worlds.
Methane normally doesn’t do much but float around in the atmosphere, but the researchers used modeling to show that under certain circumstances, this simple hydrocarbon can dramatically alter the heat transfer inside the planet, they write.
Methane usually exists as a gas, but in the upper regions of these ice worlds’ atmospheres, the methane can condense, forming droplets that fall at lower altitudes, the study authors proposed.
There they reheat and rise again, completing a cycle similar to that of water on Earth. Once the atmosphere becomes too saturated with methane, a stable layer forms. Like a wet blanket, the stable layer prevents heat from reaching the surface, which in turn
Uranus and Neptune are the outermost planets of the Solar System
These layers are most commonly found at all latitudes of the planet Neptune and around the equator and midlatitudes. But the poles of Uranus do not have enough methane to create a stable saturated layer. As a result, heat can easily rise to the surface and cause larger storms, the study found.
On the other hand, Neptune has more methane in general, and researchers have found that occasionally this methane can rise from the stable layer and disperse through the atmosphere, allowing heat to circulate and storms to form before it all collapses. calm down again.
Further work will be needed to understand how all the factors in these ice giant atmospheres interact.
This knowledge could then be used to better understand planets outside the Solar System, the study authors wrote.
