A
pole star is a visible
star, preferably a prominent one, that is approximately aligned with the
Earth's
axis of rotation; that is, a star whose apparent position is close to one of the
celestial poles, and which lies approximately directly overhead when viewed from the Earth's
North Pole or
South Pole. A similar concept also applies to planets other than the Earth. In practice, the term
pole star usually refers to
Polaris, which is the current northern pole star, also known as the
North Star.