Answer: A geostationary satellite stays over the equator, so it cannot see or serve the polar regions properly.
A geostationary satellite revolves in the equatorial plane at a height of about 35,780 km with a period of 24 hours, so it appears fixed above one point on the equator. The earth’s curvature blocks its view of the far north and south, and signals to the poles have to travel a long slanting path through the atmosphere. Polar regions are therefore studied with satellites in polar orbits.