Our Planet Earth

Our Planet Earth

Our Earth is a beautiful planet let's learn about it today.

INTRODUCTION

Earth is a planet in which we live. It is the third planet from the sun. It is the only planet in our solar system which has life on it. It has all the things needed for life to exist. The earth is covered with 75% of water.

These things are :

Water

Air

Oxygen

Moderate Temperatures

Open Ended

What do you know about Earth ?

Continents

The earth is divided into seven continents. In every continent there are many countries.

The continents are :

1. Asia

2. Africa

3. Europe

4. Australia

5. North America

6. South America

7. Antarctica.

OCEANS

The earth has 75% of water most of it is in form of glaciers and oceans. Ocean is a large water body with salty water. Our earth has five oceans namely :

1. Pacific Ocean

2. Atlantic Ocean

3. Indian Ocean

4. Arctic Ocean

5. Antartic Ocean

Globe

A globe is a miniature form of the earth. It is like a 3-D map which helps us in locating places around the world. It is like a smaller version of the earth.

Types of Globe

1. Big Globes - Are big cannot be carried easily.

2. Pocket Globes - Are small ad can be carried easily.

Multiple Choice

How many continents are there on the earth ?

• 10

• 7

• 5

• 8

Multiple Choice

How many oceans are there ?

• 2

• 7

• 5

• 6

Axis

It is an imaginary line drawn from the north pole to the south pole that passes through the centre of the earth. It has a tilt of 23.5*.The ends of the axis are called the north and south poles. The Equator is a horizontal line that divides the earth into two equal halfs. The reigon between the north pole and the equator is known as noerthern hemisphere and the reigon between the south pole and the equator is know n as the sothern hemisphere.

Motions of the earth

Earth does two movements to make life exist - Rotation and Revolution.

Rotation happens when the earth rotates on its own axis.

Revolution happens when the earth revolves around the sun in its orbit.

Orbit - Every planet revolves around the sun the path on which it revolves is called the orbit.

ROTATION

When the earth spins on its own axis it is called rotation. One whole rotation takes 24 hours which is one day. Rotation is important for occurence of day and night.

When the earth rotates the whole earth does not face the sun at the same time. So the part of the earth which faces the sun experiences day and the part of the earth not facing the sun experiences night.

If rotation does not happen half of the earth will always experience night and will be cold as no heat will be coming. Half of the earth will always experience day and will be very hot as continuous heat is coming. Life will not be possible in such extreme conditions.

REVOLUTION

When the earth revolves around the sun in it's called revolution. It takes 365 1/4 days which we aproximately say as 365 days, that is a year, to complete one revolution. Revolution is important for occurence of seasons.

When the north pole is tilted towards the sun it experiences summer. There are longer days and shorter nights. The longest day and shortest night occurs on 21 June. In the same time the opposite happens in the south pole it is winter season there. This position of the earth is called summer solstice. On 22 december the south pole is tilted towards the sun so the sothern hemisphere experiences summer. The opposite in the northern hemisphere, it experiences winter. This position of the earth is called the winter solstice.

EQINOX

Equinox happens when the whole earth receives the same amount of light and there are equal days and equal nights everywhere. There are two equinoxes one on 21 march when there is spring in the northern hemisphere and autumn in sothern hemisphere. One is on 23 september where the sothern hemisphere experiences spring and the northern hemisphere has autumn season.

LEAP YEAR

As the earth does not take exactly 365 days to revolve around the sun. It takes exactly 365 1/4 days to complete one revolution. To make it easy we call it as 365 days only and add the 1/4 day which is 6 hours four times to make a day which is then added to February every four years. This year which has 366 days instead of 365 is called a leap year. In this year February has 29 day instead of 28. We can calculate if a year is leap year or not by dividing it by four if it is divisible, then the year is a leap year.

Multiple Choice

How much time does rotation take ?

• 5 hours

• 50 hours

• 24 hours

• 6 hours

Multiple Choice

How much time does revolution take ?

• 200 days

• 555 days

• 362 days

• 365 days

Open Ended

What is a leap year

Circle of Illumination

The circle that divides the globe into day and night.

ORBITAL PLANE

The plane formed by the orbit is known as orbital plane.

VIDEO LINKS

https://www.youtube.com/watch?v=6SzjlsuyTdk

Video on rotation and revolution

https://www.youtube.com/watch?v=p3e7yhz-akk

Video on leap year

https://www.youtube.com/watch?v=1zL08Htdkh4

Summary

Open Ended

What did you learn today ?

TIME FOR RECAP !!!

Answer the questions in the upcoming slides.

Open Ended

Differenciate between summer and winter solstice.

Multiple Select

Which of the following are continents ?

• Australia

• Asia

• North America

• India

Multiple Choice

In which hemisphere is Asia located ?

• Sothern Hemisphere

• Northern Hemisphere

• Western Hemisphere

• None of the above

Open Ended

Name the two equinoxes.

Multiple Choice

What is the Equator ?

• A horizontal line that divides the earth into two equal halfs

• A line

• A vertical line

• A horizontal line on the globe