Magnetospheres are generated with magnetic materials and motions within the magnetic material. Scientists believe that as long as a planet or star has these two ingredients it can generate a magnetic field.

The terrestrial planets generate magnetospheres within the iron cores at their centers. However, Neptune has almost no iron core.

The magnetic material of Neptune is found within its icy shell. Motions within that shell produce Neptune's medium sized magnetosphere.

Magnetospheres are generated with 1.) magnetic materials and 2.) with motions within the magnetic material. As long as a planet has these two ingredients scientists believe that it can generate a magnetic field.

The Earth-like planets generate magnetospheres within the iron cores at their centers. However, Neptune has almost no iron core.

The magnetic material of Neptune is found within its icy shell. Motions within that shell produce the magnetic field.

Magnetospheres are generated with 1.) magnetic materials and 2.) with movement of the magnetic material.

The Earth-like planets generate magnetospheres within the iron cores at their centers. However, Neptune has almost no iron core.

Neptune's magnetic field is created by movement in its icy shell.