Telescope

Telescopes are used to see distant objects such as celestial and terrestrial bodies. Some of these objects may not be visible to the unaided eye. The visual angle subtended by the distant objects at the eye is so small that the object cannot be perceived.

The use of a telescope increases the visual angle and brings the image nearer to the eye. Mainly two types of telescopes are in common use:

1. Refracting telescope
2. Reflecting telescope