WHEN YOU LOOK AT THE NORTHERN SKY, you look away from the densely populated Galactic centre, so the northern sky generally appears less bright than the southern sky are the constellation Ursa magjor (the Great Bear) and Orion. Some ancient civilizations believed that the stars were fixed to a celestial sphere surrounding the Earth and modern maps of the sky and are based on similar idea. The north and sound poles of this imaginary poles of the earth, at the points where the earth's axis of rotation intersects the sphere. The Celestial Norn Polaris (the Pole Star) lies very close to it. The Celestial equator marks a projection of the Earth's equator on the sphere. The ecliptic marks the path of the sun across the sky as the earth orbits the sun. The Moon and planets moves against the background of the stars because the stars are much more distant; the nearest star outside the Solar system is (Proxima Centauri) is more than 50,000 times further away than planet Jupiter.
