ABSTRACT
The Sun is the main source of light, and without it the world would be a dark, lifeless place. Light from the Sun provides energy for plants to grow, and most animals use it to help them sense the world. This chapter focuses on the behaviour of light, and how it enables us to see objects in the world. Regardless of how it is produced, light travels outward from its source at an amazing speed of 299,792km per sec, which is an incredible 670,616,629mph. Materials which light cannot pass through are called opaque. Opaque materials either absorb or reflect the light that shines on them. In other words, they block it out and stop it travelling in a particular direction. The eyesight of birds of prey such as eagles, hawks and buzzards is 4 to 8 times keener than humans.
