\(\mathrm{d}=\mathrm{R}_{\mathrm{e}}=6.4 \times 10^{6}\, \mathrm{m}\)
Earth's magnetic field, \(\mathrm{B}=\frac{\mu_{0}}{4 \pi} \cdot \frac{2 \mathrm{M}}{\mathrm{d}^{3}}\)
\(=\frac{4 \pi \times 10^{-7}}{4 \pi} \times \frac{2 \times 8 \times 10^{22}}{\left(6.4 \times 10^{6}\right)^{3}}\)
\(\cong 0.6\) \(Gauss\)