WEEK 3: The Earth in Space

TOPIC: The Earth in Space

The earth is a planet on which man and other living things naturally live. Scientists have not found living things in any other planet. The earth is spherical in shape and it is almost like a ball. Observations from space revealed that the earth is not stationary, rather it turns round while following a path called an orbit round the sun. The earth is called a planet because it revolves round the sun. By the use of satellites, robots and space vehicles, man has gained a lot of knowledge of the first nine planets discovered by man.

The Solar System.

The solar system consists of the sun, the planets the stars and smaller celestial bodies whose movements are governed by the sun. All the planets revolve round the sun. The sun is a star in the center of the solar system. And the sun is the chief source of energy on earth. The sun is filled up of gases and is very much bigger than the earth. It luminous and radiate both heat and light energy. The nine planets that makes up solar system are:  mercury, Venus, earth, mars, Jupiter, Saturn, Uranus, Neptune, Pluto.

Mercury is the planet that is nearest to the sun followed by Venus the earth, mars, etc. Pluto is the farthest planet from the sun. Every planet is known to revolve round the sun. the direction or trajectory through which they move is called the axis. The time it takes a planet to move a complete cycle of the sun is called revolution or planet yea. Thus one year on the earth is 365 days. Every four years is a leap year.

Rotation of the earth.

Like we said earlier the earth rotates round the sun through its axis. It takes the earth about 365 days to complete its movement round the sun for one year. The rotation of the earth round its axis results in day and night. It takes the earth 24 hours to complete one rotation. The inclination of the axis of the earth creates the seasons and causes the height of the sun at noon to increase and decrease as the season changes.

The Moon.

The moon is an illuminous body which has no light of its own to give out. The moon can only give out light if it reflects some  from the sun. Moons are bodies that moves round a planet. They have no light of theirs, but can give light at night when they are able to reflect from the sun during the day. The size of the moon observed by us at night  depends at the position  at of the moon on its axis. The earth at times is positioned in such a way you can see a half moon or full moon. The moon rotates about its axis and revolves every 28 days. This is why you see one side of a moon for a very long time. Since the rotation and revolution times are the same, a day and a year are also the same length on the moon. Apart from the planets, there are also comets and asteroids which revolve round the sun. Asteroids are small planet like masses which move round the sun between the orbit of mass and Jupiter. Comets are hazy star like objects with tail moving round the sun in a non-satellite orbit.

 Class exercise

1. What are the causes of night and day on earth?
2. How many moons do the earth has.
3. Asteroids are located between planet’s  orbits

VISUAL VIDEO CLIP

PART ONE 

PART TWO