Blog 5: Jovian Magnetospheres

For this blog post, I’m going to be talking about the relative magnetospheres of the Jovian planets. As we have learned with terrestrials, magnetic fields are generated by motions of charged particles deep in their planet’s interiors. These magnetic fields create magnetospheres, which are like huge bubble that surround the whole planet and shield it from solar wind. Jupiter by far has the strongest magnetic field in our solar system, roughly 20,000 times as strong as Earth’s! Magnetospheres require an interior region of electrically conducting fluid, convection in the layer of fluid, and moderately rapid rotation. For Jupiter, the fluid region is a thick layer of metallic hydrogen. The extent of the region with rapid rotation explains the strength of the magnetic field, explaining Jupiter’s enormous magnetosphere. Jupiter’s traps far more charged particles than Earth’s because Earth lacks its source of particles. All charged particles in Earth’s magnetosphere comes from solar wind, but in Jupiter’s case it is from the volcanically active moon, Io. The many particles that Io contributes create aurorae belts of intense radiation around Jupiter, damaging orbiting spacecrafts. The other jovian magnetospheres are much weaker than Jupiter’s but still stronger than Earth’s. It depends on the size of electrically conducting layer buried in its interior. Saturn’s is weaker because it has a thinner layer of electrically conducting metallic hydrogen. Uranus and Neptune don’t have any metallic hydrogen, so their weak magnetic field must be generated in their core ocean of hydrogen compounds, rock, and metal. The size of a planet’s magnetosphere not only depends on magnetic field strength, but on pressure of the solar wind against it. Despite the weak magnetic field strength of farther planets, their magnetosphere bubbles are larger than they would be if closer to the sun. However, no other magnetosphere is full of charged particles like Jupiter’s still, because no other jovian planet has a satellite like Io. 

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