Saturn’s images, beamed back to Earth by NASA’s Cassini spacecraft in 2008, revealed that “hotspots” observed on the planet’s poles were massive cyclones, but scientists did not know exactly what could cause such powerful storms. Now, a new study has shown that small thunderstorms on the planet may eventually add up to massive, long-lived cyclones at the poles.
In a study, published in the journal Nature Geoscience on Monday, researchers at the Massachusetts Institute of Technology (MIT) said that short-lived thunderstorms across Saturn could serve as a possible mechanism for polar cyclones by building up angular momentum within the planet’s atmosphere. For the study, the researchers developed a model of Saturn’s atmosphere to simulate the effect of several small thunderstorms forming on the planet.
“Before it was observed, we never considered the possibility of a cyclone on a pole,” Morgan O’Neill, a former PhD student at MIT and the study’s lead author, said in a statement. “Only recently did Cassini give us this huge wealth of observations that made it possible, and only recently have we had to think about why [polar cyclones] occur.”
Polar cyclones on Saturn have been baffling scientists for years because the gaseous planet does not have water -- an essential ingredient for building up such storms -- on its surface. After simulating Saturn’s stormy atmosphere, the researchers found that a phenomenon called “beta drift” could make the planet’s spin cause small thunderstorms to drift toward the poles. On Earth, beta drift drives the motion of hurricanes, without requiring the presence of water, according to scientists.
The researchers ran hundreds of simulations on the model of Saturn’s atmosphere and observed that several thunderstorms experienced beta drift over time. The storms eventually accumulated enough atmospheric circulation to create a much larger cyclone at the poles.
“This mechanism means that little thunderstorms — fast, abundant, but not very strong thunderstorms — over a long period of time can actually accumulate so much angular momentum right on the pole, that you get a permanent, wildly strong cyclone,” O’Neill said in the statement.