Polaris -the centre around which the rest seems to rotate.
"Follow the 'pointer stars' at the front of the Plough's bowl to 'Polaris', the one star that doesn't change position as the Earth turns. This is because Polaris lies almost exactly along the axis of the earth; if you were at the Earth's North Pole, Polaris would be directly overhead. Many people expect Polaris to be the brightest star in the sky and are disappointed that it is not more prominent." -Night Sky, Chet Raymo.