Polar vortices on Earth and in the solar system
On Earth, polar vortices are well known and studied. These swirls of air masses, rotating around the poles, are formed due to the Coriolis force, a consequence of the Earth's rotation. In each hemisphere, these circular currents trap cold air around the poles, maintaining a certain stability in the atmospheric layers. However, when disturbed, for example by temperature variations, they can release cold air towards lower latitudes, causing extreme cold spells in temperate regions.
Polar vortices are not exclusive to Earth. NASA's Juno probe observed similar formations on Jupiter: at the planet's north pole, eight distinct vortices are organized into a complex structure, while at the south pole, five vortices are present. On Saturn, Cassini probe observations revealed equally intriguing formations, with a unique hexagonal north polar vortex and a more circular structure at the south pole.
Polar vortices have also been detected on Mars, Venus, Uranus, Neptune, and even Saturn's moon Titan. These structures vary depending on the atmospheric characteristics of each celestial body, providing scientists with valuable information about the composition and dynamics of each atmosphere.
This recurrence of swirling formations in planetary atmospheres naturally prompts researchers to wonder whether the Sun, although a star surrounded by magnetized plasma rather than a conventional atmosphere, could also host polar vortices. However, the very nature of the Sun makes this question complex and opens up new research perspectives.
photo credit: JPL-NASA/CC0 Close-up view of the planet Jupiter taken by the Juno probe. Credits: NASA
A first approach
Unlike solid planets, the Sun is a ball of plasma in constant activity. The magnetic fields that emanate from it influence the surrounding matter in unpredictable ways, making any observation of its poles particularly difficult. Currently, all observations of the Sun are limited to the side visible to us from Earth or to points of view close to the ecliptic (the plane in which the planets orbit). We have therefore never been able to directly observe the solar poles.
To try to see things more clearly, a team from the National Center for Atmospheric Research in the United States used computer models. These simulations allowed them to study magnetic dynamics and predict the probable formation of polar vortices. The researchers thus discovered that our star could well have vortices around its poles, but with unique characteristics influenced by solar magnetism.
In detail, the Sun follows an activity cycle of approximately 11 years, during which its magnetic fields change strength and polarity. This cycle is marked by periods of calm and turbulence, with a “solar maximum” at the top of the cycle, where solar storms and flares are more frequent. At this point, the magnetic field reverses, and a new polarity begins to be established at the poles.
The simulations of this study (visible below) show that the formation of solar vortices seems to be linked to this cycle of reversal of magnetic fields. At a specific point in the cycle, a phenomenon called “pole rush” occurs, where magnetic fields of opposite polarity appear at 55 degrees latitude and begin to move toward the poles. It is also during this period that polar vortices seem to form and move towards the poles following this magnetic “ring”. This pattern of vortex migration to the poles, finally disappearing at solar maximum, suggests a strong link between vortices and the magnetic behavior of the Sun.
Why is this discovery important?
These results are very valuable to scientists because we know that the Sun's magnetic field directly influences space weather and the magnetic environment around Earth. Sudden changes in solar activity can indeed affect satellites, communications systems, power grids, and even astronauts. By better understanding the functioning of the solar magnetic field, and in particular the phenomena taking place near the poles, scientists could therefore refine their forecasts of solar storms and anticipate their effects on the Earth.
If the computer simulations offer us a first fascinating glimpse of what could happen at the solar poles, – the best would nevertheless be to be able to observe these vortices directly. The Solar Orbiter mission, a collaboration between NASA and the European Space Agency, is expected to collect the first images of the Sun's poles in a few years, although it will arrive at the time of solar maximum. A subsequent mission, specifically designed to observe the poles, could thus answer more precisely the questions raised by this new study.
Source: Proceedings of the National Academy of Sciences
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
