The question of who invented the telescope is a controversial one. It is usually credited to the Dutch optician Hans Lippershey in 1608, although recent research suggests that a form of telescope may have been discovered by the Englishman Leonard Digges around 1550. However, one thing is clear - the first person to systematically use a telescope for astronomy was the Italian scientist Galileo Galilei in 1610.

The purposes of a telescope are two-fold:

1. to allow the collection of energy (i.e. photons) over a larger area so that fainter objects can be studied;
2. to provide a higher angular resolution so that objects can be studied in greater spatial detail.

We shall begin this part of the course by studying the principles of telescope optics, before moving on to look at the various different types of astronomical telescope, how they are mounted, and where they are sited.