P5- Solar System

Rotation of the Earth

• The Earth rotates on its own axis from West to East. 
• The axis is an imaginary line that passes through the North Pole and the South Pole.
• It takes about 24 hours (one day) for Earth to complete one rotation.
• At any one time, one side of the Earth will be facing the Sun.
• The half side of Earth facing the Sun will experience day.
• The other half side of Earth facing away from the Sun will experience night.
• It takes 24 hours for a place on Earth to come back to the same position.
• The rotation of Earth brings about day and night.

The Atmosphere

• The atmosphere is a layer of air surrounding the Earth.
• The atmosphere is important to us in various ways
  

1. It acts as a blanket that retains some heat from the Sun, thus keeping the temperature on Earth fairly steady.
2. It protects Earth from the harmful ultra-violet rays from the Sun.
3. The oxygen in the atmosphere is used for respiration.
4. The carbon dioxide in the atmosphere is used for photosynthesis.
5. The other gases in the atmosphere are required for many other processes.

Importance of the Sun

• The light energy given out by the Sun enables plants to photosynthesize, thus enabling the survival of all living things because all living things depend directly or indirectly on plants for food.
• The light energy given out by the Sun enables animals to see and respond to changes in their surrounding.
• The heat energy given out by the Sun keeps organisms warm and provides a suitable temperature for various life processes to take place.
• The heat energy given out by the Sun enables the evaporation of water, thus ensuring the continuity of the water cycle to provide a continuous source of water supply to the organisms on Earth.

Position of the Earth from the Sun

• If the Earth were nearer to the Sun, the Earth would receive too much heat energy and the temperature would increase drastically. The oceans would dry up and most living things would die because of the heat.
• If the Earth were further from the Sun, the Earth would receive too little heat from the Sun and the temperature would fall. The oceans would freeze and most living things would not be able to survive the cold weather. 

REMINDER: Please read up on this chapter in your science guide book.