Assertion: magnetic field | /r/HasAspect | source
Facets:
value: in magnetosphere
type: LOCATION
value: in the ionosphere
type: LOCATION
value: in the crust
type: LOCATION
Source sentences:
text: A magnetic field has no sources or sinks (Gauss's law for magnetism), so its field lines have no start or end: they can only form closed loops, extend to infinity in both directions, or continue indefinitely without ever crossing itself.
text: In addition to sources in the Earth's core the magnetic field observable at the Earth's surface has sources in the crust and in the ionosphere and magnetosphere.