Figure 9-18 Babcock’s Magnetic-Dynamo Model Magnetic field lines tend to move along with the plasma in the Sun’s outer layers. Because the Sun rotates faster at the equator than near the poles, a field line that starts off running from the Sun’s north magnetic pole (N) to its south magnetic pole (S) ends up wrapped around the Sun like twine wrapped around a ball. The insets on the far right show how sunspot groups appear where the concentrated magnetic field rises through the photosphere.