4 Auroras are beautiful They are natu ral displays of colored light that sometimes appear in the night sky They occur mainly in the northernmost parts of the Northern Hemisphere and the southernmost part of the Southern Hemisphere Auroras in the Northern Hemisphere are called the northern WHAT ARE AURORAS Since it is in the Northern Hemisphere this colorful aurora is the aurora borealis
5 lights or aurora borealis In the Southern Hemisphere auroras are called the southern lights or aurora australis Auroras are named for Aurora the Roman goddess of the dawn Auroras take many shapes and forms with arcs and rays of colored light being the most common The light may also look like shimmering curtains bands waves or clouds An aurora constantly changes shape as the light moves across the sky The light also may brighten and fade A hemisphere is one half of Earth The Northern Hemisphere is the half north of the Equator and the Southern Hemisphere is the half south of the Equator VOCABULARY These lights over the Australian island of Tasmania are the aurora australis
6 Auroras often look more clearly defined when they appear closer to Earth’s surface They seem to fade away as they appear farther up in the sky Different aurora forms have different names In the corona form rays seem to meet overhead in a starlike shape In the flame type tonguelike rays ripple upward Verti Here you can see the beautiful corona form of an aurora BEAUTIFUL FORMS
7 cal rays rising from curving bands are called draperies which look almost like curtains The uniform arc is the most stable form of aurora It can sometimes last for hours without seeming to change in shape However most aurora forms move Their movement is often de scribed as dancing Auroras come in many colors including red yellow green blue and violet However the most common colors for auroras are light green and pink Look at the aurora photos in this book Can you think of words of your own to describe the forms you see THINK ABOUT IT The yellowish-green color of this flame type aurora is the most commonly seen color
