Planetary Magnetic Field Strength Calculator Formula
Understand the math behind the planetary magnetic field strength calculator. Each variable explained with a worked example.
Formulas Used
Surface Magnetic Field (equator)
b_field = (1e-7) * dipole_moment / pow(planet_radius, 3)Field (Gauss)
b_field_gauss = (1e-7) * dipole_moment / pow(planet_radius, 3) * 1e4Polar Field
b_pole = 2 * (1e-7) * dipole_moment / pow(planet_radius, 3)Variables
| Variable | Description | Default |
|---|---|---|
dipole_moment | Magnetic Dipole Moment(A m2) | 7.94e+22 |
planet_radius | Planet Radius(m) | 6371000 |
How It Works
Planetary Magnetic Field
A planet's magnetic field can be approximated as a dipole near the surface.
Equatorial Field
B_eq = (mu0 / 4pi) * M / R cubed
where mu0/(4pi) = 1e-7 T m/A.
Polar Field
B_pole = 2 * B_eq
Earth's dipole moment is about 7.94 x 10^22 A m2, giving an equatorial field of roughly 3 x 10^-5 T (0.3 Gauss).
Worked Example
Earth: dipole moment = 7.94e22 A m2, radius = 6.371e6 m.
dipole_moment = 7.94e+22planet_radius = 6371000
- 01B_eq = 1e-7 * M / R cubed
- 02R cubed = (6.371e6)^3 = 2.586e20
- 03B_eq = 1e-7 * 7.94e22 / 2.586e20
- 04B_eq = 3.07e-5 T = 0.307 Gauss
Ready to run the numbers?
Open Planetary Magnetic Field Strength Calculator