EARTH

Earth is perfect for plants, animals, and people to live on. It is only planet in our solar system known to have living things. It has the right combination of air, water, sunlight and warmth. Because about three-quarters of the Earth's surface is covered with water, Earth is sometimes called the 'Blue Planet'.

Earth is about 150 million km away from the Sun. If you drove a car, it would take you about 170 years to reach Sun! If Earth were closer to the Sun, it would be too hot to live on and if it were further from the Sun, everything on it would soon be covered with ice.

Earth is slightly tilted on its axis and this causes seasons. The side that tilts towards the Sun as Earth turns has summer. It is warm. And the side that tilts away from the Sun has winter, which is very cold. Earth is the fifth largest planet in our solar system. It weighs 6 million million million million kg and is about 40 thousand km around its middle. It has one moon which takes 27.3 days to move around the Earth.

At the centre of  Earth is a hard core of solid metal. After that is a thick layer of soft hot rock and the crust is a thin layer of hard rock. Earth is something like an egg! Earth takes 23 hours and 56 minutes to rotates on its axis once. Its rotation causes day and night.

Earth travels around the Sun once every 365 1/4 days. To make it easy, we have made one last 24 hours and one year last 365 days. Then for every fourth year, we add one extra day to February. This extra long year is called a leap year and has 366 days.