Large-scale convection in planetary or stellar interiors plays a significant role but it is difficult to reproduce the central force field of those systems in experimental studies. A technique to approximate a central force field through the magnetic field from magnets acting on a magnetic liquid is presented. The thermomagnetic convection in a spherical shell filled with a magnetic liquid is analyzed in the context of a terrestrial laboratory using a 2D Finite Element model. Two configurations of magnetic fields were investigated, one resulting in a radially decreasing force field, and the other in a radially increasing force field. The results suggest that, while the actual force field does not reproduce the central gravity in planetary interiors accurately, it captures the essential qualitative character of the flow unlike other terrestrial experiments, which were either dominated by gravity or by a cylindrical radial force field. It is therefore suggested that such an experiment would provide a useful tool to investigate thermal convection in planetary interiors. © 2005 Author(s). This work is licensed under a Creative Commons License.