Abstract: A sighting device for aiming an astronomical telescope. The sighting device comprises a tubular housing which is removably mountable in the eyepiece holder of the telescope. A light source is mounted within the tubular housing for projecting light into the eyepiece holder to thereby form a beam of light emergent from the front end of the telescope. This beam of light provides a visual indication of the direction in which the telescope is aimed, and the telescope may be aimed at a desired object or area by reference to the beam of light. After the telescope has been aimed, the sighting device is removed and replaced by a normal eyepiece.