ABSTRACT
The Earth rotates around an imaginary axis that runs through its center from the North Pole to the South Pole. It takes approximately 24 hours for the Earth to rotate around its axis one time. The region of the globe facing the sun will experience daylight while the opposite side of the globe experiences night. Every day, the sun appears to cross the sky from east to west because of the Earth's rotation. For thousands of years, people have noticed that shadow length changes during the day. The length of shadows increases after the summer solstice and decreases after the winter solstice. The sun is lowest in the sky in winter and highest in summer. In winter months, the sun is low in the southern sky and shadows cast will be longer than those made in the summer. The greenhouse effect is important. Without the greenhouse effect, the Earth would not be warm enough for humans to live.
