The constant velocity field and the background radial component of the magnetic field are 0.9 RJ . The projection is the coplanar plane with the central meridian at 180° in System III coordinates (highlighted in gray); The central meridian is the zero line for steady flow. The color scale of the background magnetic field model is linear between the indicated ranges. Flow velocity is scaled with latitude to calculate the polar coordinates of meridians; The peak velocity (relative to the equatorial jet) is 0.86 cm.−1. debt: Nature (2024) DOI: 10.1038/s41586-024-07046-3
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The constant velocity field and the background radial component of the magnetic field are 0.9 RJ . The projection is the coplanar plane with the central meridian at 180° in System III coordinates (highlighted in gray); The central meridian is the zero line for steady flow. The color scale of the background magnetic field model is linear between the indicated ranges. Flow velocity is scaled with latitude to calculate the polar coordinates of meridians; The peak velocity (relative to the equatorial jet) is 0.86 cm.−1. debt: Nature (2024) DOI: 10.1038/s41586-024-07046-3
A team of planetary scientists affiliated with several institutions in the United States has discovered a jet in Jupiter's atmosphere that fluctuates with roughly quadrennial periods. In their paper Published In the journal NatureThe team describes how they discovered the jet and studied its properties using data from the Juno spacecraft.
Previous research has shown that Jupiter has a large magnetosphere, parts of which extend as far as Saturn's orbit. The planet's magnetic field is approximately 20 times greater than Earth's, making it a good target for research. Jupiter is a gas giant—it also has no crust—making it a good target. This makes it much easier to study the dynamo that maintains the magnetosphere compared to the dynamo that creates the Earth's magnetic field.
NASA sent a probe specifically designed to measure and map the planet's magnetic field—the Juno probe—launched in 2011 and entering Jupiter's polar orbit in 2016. Since then, it has been transmitting valuable data about many aspects of the planet. magnetic field. In this new effort, the researchers focused on data surrounding the atmospheric jet.
Atmospheric jets are high-speed currents moving through a planet's atmosphere, similar in some respects to the jet stream on Earth. In this new effort, the research team focused on a jet in Jupiter's ring region known as the „Great Blue Spot.” By studying data describing the jet's characteristics, the researchers found that it has some wave-like fluctuations over roughly four-year periods.
The research team initially thought it might be related to convection-driven flows from the metallic hydrogen pool that forms part of the planet's inner atmosphere. But such a jet would certainly have a time span of centuries, not years. That led them to develop two alternatives.
First of all, they are caused by oscillations created around the planet's axis. Second, they are caused by Alfvén waves – the type that propagate along magnetic field lines. The researchers hope that more data from Juno will better characterize the fluctuations they detected, perhaps leading to a better understanding of the planet's dynamo.
More information:
Jeremy Bloxham et al, A rapidly time-varying equatorial jet in Jupiter's deep interior, Nature (2024) DOI: 10.1038/s41586-024-07046-3
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