Where does Earth 's magnetic field point during magnetopause ?
formula_1 where formula_2 and formula_3 are the density and velocity of the solar wind , and " B " ( " r " ) is the Magnetic field strength of the planet in SI units ( " B " in T , μ0 in H / m ) Since the dipole magnetic field strength varies with distance as formula_4 the magnetic field strength can be written as formula_5 .