1 Observing with the naked eye
The human eye is an amazing optical system which has evolved to operate in a wide range of conditions. Human vision is good at picking out moving objects at both high and low light levels. In bright daylight conditions the human eye also has an excellent ability to distinguish between subtle colour and brightness differences and to detect small objects. As light levels fall however, the eye needs to adapt to work in darker conditions, with less total light available to form an image.
In this section you will learn how your eyes adapt to dark conditions and how to use your adapted vision to its best effect for astronomical observing.