Equatorial mounting & Newtonian telescope

Equatorial mounting The usual method of mounting an astronomical telescope. The mounting has one axis (polar axis) pointing towards the celestial pole, and therefore parallel to the Earth's axis. The telescope is carried on another axis (the declination axis) at right-angles to the polar axis. With this mounting, the telescope can readily follow a star across the sky.

Newtonian telescope A reflecting telescope designed by Isaac Newton in 1668. The principle is still widely used. In a Newtonian reflector, the light is gathered by a parabolic mirror and reflected back up the telescope tube to a plane mirror angled at 45*. This mirror deflects the light to the side of the tube, where an eyepiece is located.