Ganymede: The largest icy moon of Jupiter

Following up on our last blog about the icy moons of Jupiter, in this blog we start off with understanding the largest moon of the planet and our Solar System, Ganymede! Although we have only a few measurements from the moon through the Galileo and Juno missions orbiting Jupiter, we have quite a lot of information from them.

Ganymede is a very unique moon. It is the only moon we know of that is capable of generating its own magnetic field, possibly through a dynamo. This means that there is some conducting liquid in which convection is taking place that is producing a magnetic field of the order of ~103 nT. This dynamo is expected to be an iron and iron sulphide alloy.

While the most important and interesting insight about Ganymede is the dynamo, another fascinating feature is the presence of a subsurface ocean. However, we are still unsure if the field we observed was from an ocean or just part of the dynamo signal. When we model magnetic field data of the moon, both these possibilities arise and hence to confirm which of them are true, we would require more data from around the moon.

Once we have a wealth of measurements from future missions, we would be able to better model the magnetic field as well as other observations like the gravity field which will help us better understand its interior structure. In the meantime, drop your questions about Ganymede below and let us know what you are curious to find about the moon!

Image: Ganymede from Galileo. Credit: NASA.

Shivangi Sharan is a postdoctoral research associate at Imperial College London, working on prioritising the research that will be carried out using the JUICE magnetometer data. Previously, she has worked on the interior of Mars and Jupiter using their magnetic observations. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.


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