Saturn and its dazzling system of ice rings have been an object of admiration for a long time. The sixth planet from the Sun still holds many mysteries, partly because of its remoteness, direct observation is difficult, and partly because this gas giant’s atmosphere consists mainly of hydrogen and helium. By learning more about this, it will be possible to get an idea of the creation of the solar system itself.
One of the mysteries of Saturn involves a massive hexagon-shaped storm at the North Pole. The hexagonal vortex is an atmospheric phenomenon that has attracted the attention of planetary scientists since its discovery in the 1980s by the American Voyager program and the subsequent visit in 2006 of the US-European Cassini-Huygens mission. The storm is about 20,000 miles in diameter and is limited by winds that blow at speeds of up to 300 miles per hour. A hurricane like this does not exist on any other known planet or moon.
Jeremy Bloxham, professor of geophysics at Mallinkrodt, and research assistant Rakesh K. Yadav, who works in Bloxham’s laboratory at the Harvard Division of Earth and Planetary Sciences. In a recently published article in PNAS, researchers began to puzzle over how the vortex originated.
“We regularly see storms on Earth, and they are always spiral, sometimes round, but never have hexagonal segments or polygons with edges,” Yadav said. “This is really amazing and completely unexpected. How did such a large system come about and how can it remain unchanged on this large planet? ”
Having created a 3D simulator of Saturn’s atmosphere, Yadev and Bloxham believe they are close to the answer.
In their paper, scientists believe that an unnatural-looking hurricane occurs when atmospheric currents deep within Saturn create large and small eddies (cyclones) that surround a larger horizontal jet stream blowing eastward near the planet’s north pole, which also has a series of storms inside. Smaller storms interact with the larger system and as a result effectively pinch the eastern stream and confine it to the top of the planet. In this process, the stream turns into a hexagon.
“This stream revolves around the planet and must coexist with these localized storms,” Yadav said. “Imagine we have a rubber band and we put a bunch of small rubber bands around it, and then we just squeeze it all on the outside. This center ring will shrink and form a strange shape with a certain number of edges. It’s basically the physics of what’s going on. We have these smaller storms, and they are essentially compressing the larger storms in the polar region, and since they must coexist, they must somehow find space for each system. By doing this, they end up forming this polygonal shape. ”
The model, created by the researchers, suggests that the storm is thousands of kilometers deep, far below Saturn’s cloud tops. The simulation simulates the outer layer of the planet and only covers about 10% of its radius. Over the course of a month, computer simulations have shown that the phenomenon of deep thermal convection, which occurs when heat is transferred from one place to another due to the movement of liquids or gases, can unexpectedly cause atmospheric currents that create large polar cyclones and high-latitude eastern flow … When they mix at the top, an unexpected shape is formed, and since storms form deep within the planet, scientists say this makes the hexagon violent and tenacious.
Convection is the same force that causes tornadoes and hurricanes on Earth. It’s like boiling a pot of water: heat from the bottom is transferred to a colder surface, causing the top to bubble. It is believed that this is what causes many storms on Saturn, which does not have a solid surface like Earth.
“The hexagonal flow on Saturn is a striking example of turbulent self-organization,” the researchers say. “Our model simultaneously and self-consistently creates alternating zonal jets, a polar cyclone, and hexagonal polygonal structures like those seen on Saturn.”
But there was no hexagon in the model. Instead, the researchers saw the shape of a nine-sided polygon that was moving faster than Saturn’s storm. However, the form serves as a proof of concept for a general thesis of how a majestic form is formed and why it has remained relatively unchanged for almost 40 years.
Interest in Saturn’s hexagonal storm dates back to 1988, when astronomer David A. Godfrey analyzed data from the Saturn flyby of the Voyager spacecraft in 1980 and 1981 and reported the discovery. Decades later, from 2004 to 2017, NASA’s Cassini spacecraft captured some of the clearest and best-known images of the anomaly before plunging into the planet.
There are many hypotheses about how