phy1020.DVI

Figure 33.4: The direction of the past geomagnetic field is recorded in the Earth’s crust on either side of the
mid-Atlantic ridge, in much the same way as information is stored on a magnetic tape by a tape recorder.
(Credit: U.S. Geological Survey.)

Solar

Wind Geomagnetic Tail

Magnetopause

Polar Cusp

Figure 33.5: The Earth’s magnetosphere. The leftmost curve is thebow shock, a shock wave in the solar
wind. Themagnetopauseshown here is the outer boundary of the Earth’s magnetic field. The region between
the magnetopause and the bow shock is called themagnetosheath. The Sun is outside the figure, to the left.
(Credit: NASA.)