
This hands-on activity for introductory physics is designed to help students form a deeper understanding of planetary magnetic fields by building physical models and using a smartphone app as a magnetometer to map magnetic field vectors. Students work in groups to model two very different planets: one mimics the strong magnetic field of Earth; the other mimics a Mars-like planet without an active, robust magnetic field. The smartphone magnetometer will be used to visualize a planetary dipole field (representing Earth) and a Planet X with a disordered planetary field comprised of localized remnants of magnetization in the crust (similar to Mars). Students will engage in scientific reasoning to explain why planetary magnetic field vectors vary and how the presence of a magnetic field is essential to life on a planet's surface.