5.3 The Perfect Placement Of The Earth In The Solar System

Planets In The Solar System

1) The nine planets in the Solar System are at different distances from
    the Sun.

2) The Sun gives out heat and light which reach the planets.

3) The inner planets
    (a) Mercury, Venus, Earth and Mars are four planets that are nearest to
         the Sun.
    (b) These planets are made of rocks.
    (c) Each inner planet has an atmosphere.

4) The outer planets
    (a) Jupiter, Saturn, Uranus, Neptune and Pluto are called the outer planets
         or gas glants.
    (b) They are mainly made of gases.

                   Very hot                                                                                                   Very Cold
                                                                    Distance increases
                                                               Temperature decreases


Mercury




 ~ Nearest to the Sun.
 ~ Its temperature is too high to support
    life.








Venus





~ Second planet from the Sun and the nearest
   planet to Earth.
~ The hottest planet in the Solar System as a
    large amount of heat is trapped in its atmosphere.






Earth

~ Third planet from the Sun.
~ The only planet where there is life.
~ Has air, water and a suitable temperature.








Mars

~ A cold planet where almost all its water is
   frozen. No life exists here.
~ Its surface is covered with a thin atmosphere
   of carbon dioxide.
~ Also called the red planet because its surface
   is covered with red dust.





Jupiter

~ The largest planet.
~ All other planets can fit inside it.
~ Made up of gas.
~ Too cold to support life.







Saturn

~ The second largest planet.
~ The most beautiful planet as it is
   surrounded by three wide rings.
 ~ Made up of gas.
~ Colder than Jupiter and too cold to
   support life.





 Uranus

~ A greenish blue planet because of the
   presence of methane in its atmosphere.
~ Surrounded by narrow rings.
~ Lies on its side as it orbits the Sun.
~ Much colder than Saturn.







Neptune





~ Surrounded by a faint ring system.
~ Covered with a blue ocean of liquid
   methane.
~ As cold as Uranus.








Pluto

~ The smallest planet and furthest from
   the Sun.
~ The coldest of all the planets.








5) The placement of Earth in the Solar System makes it a perfect planet
     to support life. As the third planet from the Sun, it receives enough
     light and heat from the Sun.

 ~ Moderate surface temperature
~ 70% of the Earth's surface is covered
   with water.
~ A layer of atmosphere surrounds the
   Earth






6) The temperature of the Earth is suitable to support life because it is not too
    hot or too cold.

7) The Earth's surface contains enough water for the survival of living things.

8) The atmosphere of Earth consists of gases in the correct composition to
    support life.
    (a) Oxygen is needed for breathing.
    (b) Carbon dioxide is needed for plants to make food.
    (c) It protects the Earth from harmful rays of the Sun.

9) (a) The other planets either receive too much or too little heat.

    (b) The atmosphere of the other inner planets is too thin and poisonous to
          living things. For example, 95% of the atmosphere on Mars consists of
          carbon dioxide. The atmosphere of the outer planets is also not suitable
          to support life.

    (c) These planets connot support life because they

• are either too hot or too cold
• do not have enough air and water

10) If the Earth were much further from the Sun:         

• The temperature on Earth would drop drastically. It would be very much cloder.
•  Huge sheets of ice would cover most parts of the Earth.
• All living things would die.

11) If the Earth were nearer to the Sun:

• The temperature on Earth would rise and the condition would become hotter.
• Water on Earth would evaporate. Deserts would be formed.
• All plants and animals would die because there would be no water.