Also called residual magnetism, refers to the permanent magnetization preserved within the ferromagnetic minerals inside rocks, like meteorites. The presence of a magnetic field assumes and requires a differentiated The body from which a meteorite or meteoroid was derived prior to its ejection. Some parent bodies were destroyed early in the formation of our Solar System, while others like the asteroid 4-Vesta and Mars are still observable today. that contained a liquid In the context of planetary formation, the core is the central region of a large differentiated asteroid, planet or moon and made up of denser materials than the surrounding mantle and crust. For example, the cores of the Earth, the terrestrial planets and differentiated asteroids are rich in metallic iron-nickel. sometime in its past. When a rock cools below its Curie temperature, it acquires its primary component of remanence magnetism (thermo-remanent magnetism), and preserves its parent body’s magnetic field. Rocks can also contain evidence of superimposed secondary components of natural remanent magnetism. Natural remanent magnetization forms the basis of The discipline of inferring the Earth’s or any other differentiated parent body's ancient magnetic field and former continental positions through study of remanent magnetization in old rocks from the time of the parent body's formation. In order to study the paleomagnetism of a specimen, the remanent magnetic fields must not.