The magnetic equator is the imaginary line on Earth's surface connecting all points where the geomagnetic inclination (dip) is zero — i.e., the field is purely horizontal. This is also, to first approximation, the locus of minimum total geomagnetic field intensity, since field intensity in a dipole approximation is minimum at the magnetic equator and increases toward the magnetic poles.
Per the dipole field intensity formula B(λ) = B0√(1+3sin²λ) (λ = magnetic latitude), field intensity is minimum when λ=0, i.e., at the magnetic equator, and...
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