Giant waves have been found swirling in the plasma at Jupiter’s boundary magnetospherescientists found.
Data from Juno suggests that the Jupiter probe regularly passes through these waves, invisible to the naked eye, as it orbits the giant planet. The discovery helps astronomers understand how mass and energy are transferred from the solar wind to the Jovian planetary environment.
Actually, such waves are unknown in the Solar System. It is given Kelvin-Helmhotz waves, and occur when there is a difference in velocity at the boundary between two fluids. They can commonly be seen where the wind blows across the surface of lakes and oceans, between currents in wateror even among bands of clouds in a planet’s atmosphere.
They are noticed by the boundary of the Earth’s magnetosphere as well, not to mention near Saturn. They are the conditions under which they form which is not well understoodhowever, so some clues could be found if they are found in the vicinity of Jupiter.
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“The Kelvin-Helmholtz instability is a fundamental physical process that occurs when solar and stellar winds interact with planetary magnetic fields throughout our Solar System and throughout the universe,” says astrophysicist Jake Montgomery of the University of Texas at San Antonio (UTSA) and the Southwest Research Institute (SwRI).
“Juno observed these waves during many of its orbits, providing conclusive evidence that the Kelvin-Helmholtz instability plays an active role in the interaction between the solar wind and Jupiter.”
Even though there is not much pressure in space, the force of diffusing particles is not zero either. A magnetosphere is a type of bubble plasma space environment created by an object’s magnetic field, defined by the magnetopause. This is the limit at which the pressure from the wind that flows steadily from the Sun, the solar wind, balances the pressure of the magnetosphere.
The solar wind blows at quite high speeds from the Sun to the outer Solar System, while the plasma inside the magnetosphere does its thing, swirling around the planet. So the interface between the two can get interesting.
The environment around Jupiter is a wild, wild place. Jupiter Magnetic field is hugeand its volcanic moon Io is powerful source of charged particles, spinning matter into a giant tower of plasma that surrounds the giant gas giant. Jupiter’s moon Ganymede generates a fairly strong magnetic field of its own.
The discovery of Kelvin-Helmholtz waves at Jupiter’s magnetopause will help astronomers understand the complex interactions taking place in Jovian space.
“Juno’s extensive period near Jupiter’s magnetopause enabled detailed observations of phenomena such as the Kelvin-Helmholtz instability in this region,” says astrophysicist Robert Ebert of SwRI and UTSA.
“This solar wind interaction is important because it can transport plasma and energy across the magnetopause, into Jupiter’s magnetosphere, driving activity within that system.”
The waves were not detected in many of Juno’s magnetopause traverses, and this also has important implications. Studying the conditions under which these waves are generated could help to discover how they form, which has wider implications.
For example, wrinkles have been detected at the heliosphere – the boundary between the solar wind and interstellar space, far beyond the planets. Understanding what drives Kelvin-Helmholtz waves could help identify the dynamics at play at the boundary of the Solar System.
The research is published in Geophysical Research Letters.