Beautiful Planet - "Earth"
Earth is our planet. The earth formed 4,600 million years ago.It glowed red, hot and the molten metals sank to
its centre while the lighter rocks floated to the surface.
In the deep of our planet's heart there is a metal core of iron and nickel that is larger than the moon and almost
as hot as the surface of the Sun. Around the core is wrapped a thick layer of hot rock called the mantle.
Thickness of mantle is 2900 Km. Around the mantle is third layer called the crust, which forms the rocky surface
of the earth on which we live. Thickest part of the crust are about 60 Km. deep, it would be as the apple's
skin.Asthenosphere and lithosphere are parts of mantle. These plates are constantly moving,causing the
continents to drift apart, mountains to form, the ground to shake and volcanoes to errupt. Temperature of
inner core is upto 7,000 degree celcius. Mass of the earth is 5900 billion billion tonne.
The earth belongs to a family of nine Planets, each of which is in orbit (travelling) around the sun. Mercury,
Venus, Mars and Pluto are rocky wastes. The giant planets Jupiter, Saturn, Uranus and Neptune are globes
of gas and ice particles. Together they make up the 'Solar System'. It's also includes many Planets,asteroids
and comets(which have long tails of dust and gas). The Sun is centered of the Solar System. Without Sun's
heat and light the earth would be a frozen, dead world.
Only The earth has water in its oceans and enough oxygen in its atmosphere to support animal life. The
earth's original atmosphere probably contained large amounts of Carbon dioxide. As plants developed on
earth they used the carbon dioxide to make food and released the oxygen on which all animal life depends.
The earth is habitable because it is at just right distance from the Sun. It's time to orbit the Sun about
365 days 6 hours. Life began in the oceans about, 3500 million years ago with tiny, microscopic life-forms.
Animals and plants started to live on the land about 400 million years ago.
Thus, Our Earth is different planet from others planet.