Page 251 - New Medley 4 Semester 2 PDF (Merged)

of gaseous rings around it. The last four planets are far from our Earth and can

be seen only with the help of a telescope.

Knowledge Zone
If you remember this mnemonic ‘My Very Excellent Mother Just Sent Us Noodles’, you can write the
names of all the eight planets in their correct order from the sun. The first letter of each of these
words reminds the first letter of a planet’s name.

1 • Understanding

Fill in the blanks.
1. A is a huge ball of hot gases which gives out heat and light.
2. The fixed path on which the Earth revolves around the sun is called .

3. A is a heavenly body that revolves around a star.
4. Pluto is now called a planet.

THE EARTH

The Earth is a unique planet in our solar system
as it has air and water and hence life on it. Crust

Life on Earth would have not been possible Mantle
without the sun. The sun is the source of all Outer core

forms of energy on the Earth. Inner core

The Earth is about 4 to 5 billion years old. It
has three main layers:
Inside of the earth
 Crust: It is the outer surface of the Earth.

The humans, plants and animals live on the crust.
The Earth’s crust is about 30 kilometres thick.

 Mantle: It lies below the crust. It is made up of hot

molten rocks. It is about 3000 kilometres thick.

 Core: It is the innermost layer of the Earth. It is made
up of iron, nickel and some other metals. The core is
extremely hot with very high temperatures reaching

up to 5700°C. It also has a great pressure. A volcano

249