Open the book and discover the city at night. What’s that glowing in the dark? What kind of light does it give out? Do you know what was used for lighting in the past?

Look at all the streetlamps and huge advertising boards in the city – their light is so clear and strong that it illuminates the night sky. This phenomenon of man-made light dispersed in the atmosphere has a special name. Read this book and find out what it is. And if you turn off the light, the book will light up your room!