Why do Jupiter’s storms rotate backwards compared to those on Earth? Scientists now think they have an answer – and it’s all to do with gas flowing upwards from deep within the giant planet.
On Earth, the Coriolis effect causes our storms to rotate in the same direction as the rotation of the planet, but on Jupiter they rotate in the opposite direction. This new study, by scientists at the University of Alberta in Canada and the Max Planck Institute for Solar Research (MPS) in Germany, shows that an interaction between the layers of Jupiter’s atmosphere is the key to this phenomenon. The research is published in the journal Nature Geoscience.
Jupiter is made of mostly hydrogen and helium, and within 90 percent of the planet’s radius, the high pressure from the atmosphere above makes this mixture metallic and able to conduct electricity. Beyond this region, though, the gas is “normalized” in its non-metallic, gaseous state.
The interaction of rising gas and this outermost layer produces the weather patterns we can see. But on Earth the vortices of storms form at the bottom of these rising masses of air, whereas on Jupiter the vortices form at the top, in this upper layer of the atmosphere 7,000 kilometers (4,350 miles) thick. According to the model, this accounts for the backwards movement of Jupiter’s storms relative to our planet.
The new model is pretty good, but it still can't explain Jupiter's fascinating Great Red Spot. Shown is a false color image of the storm from Voyager 1. NASA
"Our high-resolution computer simulation now shows that an interaction between the movements in the deep interior of the planet and an outer stable layer is crucial," Johannes Wicht from the MPS said in a statement.
For the first time, the model was also able to successfully explain why Jupiter’s whirlwinds appear in wide bands north and south of the equator. It was within one of these bands that the mighty anticyclone known as the Great Red Spot, three times the size of Earth, has raged for more than 400 years.
However, as good as this new model is, it was unable to explain how anticyclones on Jupiter can last for many years, with storms in the simulation normally dissipating after just a few days. It suggests there is still much about Jupiter, particularly its Great Red Spot, that we still do not know.
"We are just beginning to understand Jupiter’s weather phenomena," Wicht explained in the statement. "In addition to its size and durability, the Red Spot has other special features such as its characteristic color. Additional processes seem to be involved here that we don’t yet comprehend."