The Earth

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THE EARTH

1.HOW DID THE EARTH BEGIN ?
Ans: Around 4.6 billion years ago, neither the Earth nor any of the other planets existed. There was just this vast, dark, very hot cloud of gas and dust swirling around the newly formed Sun. Gradually,the cloud cooled and the gas began to condense into billions of droplets. Slowly these droplets were pulled together into clumps by their own gravity and they carried on clumping until all the planets, including the Earth, were formed.But it took another half a billion years before the Earth had cooled enough to form a solid crust with an atmosphere around it.

2.HOW BIG IS THE EARTH ?
Ans: Satellite measurements show it is 40,075 km around the equator and 12,757 km across. The diameter between the poles is slightly less by 43 km.

3.HOW OLD IS THE EARTH?
Ans: The Earth is about 4.6 billion years old. The oldest rock is about 3.8 billion years old. Scientists have also dated meteorites that have fallen from space, and must have formed at the same time as the Earth.

4.WHAT SHAPE IS THE EARTH?
Ans: The Earth is not quite a perfect sphere. Because it spins faster at the equator than at the Poles,Earth bulges at the equator. Scientists describe Earth’s shape as “geoid”,which simply means Earth-shaped!

5.WHAT’S SO SPECIAL ABOUT THE EARTH?
Ans: The Earth is the only planet with temperatures at which liquid can exist on the surface and is the only planet with an atmosphere containing oxygen. Water and oxygen are both needed for life.

6.WHY DOES THE EARTH SPIN?
Ans: Earth spins because there is nothing to stop it spinning. The Sun’s gravity keeps it in orbit.

7.EXACTLY HOW LONG IS A YEAR?
Ans: Every year the Earth travels once around the Sun. This epic journey covers a distance of 938,886,400 km and takes exactly 365.24 days,which gives us our calendar year of 365 days. To make up the extra 0.24 days, we add an extra day to our calendar at the end of February in every fourth year which is called the leap year and then we have to knock off a leap year every four centuries.

8. HOW LONG IS A DAY?
Ans: A day is the time Earth takes to turn once. The stars move to the same place in the sky every 23 hours, 56 minutes and 4.09 seconds (the sidereal day). Our day (the solar day)is 24 hours, because Earth is moving around the Sun, and must turn an extra for the Sun to be in the same place in the sky.

9. WHO WAS COPERNICUS?
Ans: In the 1500 s, most people thought the Earth was fixed in the centre of the universe, with the Sun and the stars revolving around it. Nicolaus Copernicus(1473-1543) was the Polish astronomer who first suggested the Earth was moving around the Sun.