Jupiter's giant moon Ganymede is the only known moon to have its own magnetic field — and according to new research, it may be heated through a process "that has not been observed anywhere else to date."
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Ganymede, one of the four Galilean moons orbiting Jupiter, is the largest moon in the solar system. With a diameter of nearly 5,300 kilometers, it is over 1,600 kilometers larger than the Moon and slightly larger even than Mercury, the smallest planet in our solar system.
This unique moon has an inherent magnetic field, discovered in 1996 by NASA's Galileo spacecraft. The field is created through a process called a "dynamo," which is powered by the electrically conductive, churning liquid iron in its core.
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However, how this mechanism formed remains a subject of intense scientific debate. In a study published May 6 in the journal Science Advances, researchers propose a new mechanism that suggests Ganymede's metallic core and dynamo may have formed later than previously thought, as molten masses of iron sank into the moon's interior. In fact, this process may still be ongoing today.
The "heating-induced dynamo" presented in the study works in contrast to traditional theories of how magnetic fields are created. Classical theories hold that such mechanisms form early in the history of large celestial bodies, such as Earth, and then gradually cool.
In this new model, molten masses of metal sink into Ganymede's interior, feeding its core and strengthening its magnetic field. These masses are heated primarily through two mechanisms: radioactive heating and tidal heating.
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This heat powers the dynamo that creates Ganymede's magnetic field. Magnetic fields are considered essential for protecting life from harmful solar and cosmic radiation, which is why they are a key requirement in most searches for habitable planets.
