Did you know 54| Origins of earth
Our earth is the fifth largest of the nine planets which go around the sun. It spreads through space at about 30 kilometers every second, taking one year to complete the round.
Earth also spins around its orbit once every 24 hours. The earth is not a perfect ball or sphere in shape. It is 12,756 kilometers across its equator (middle) and 12,714 kms from pole to pole (top to bottom). This shape can be called geoid shape. The distance around the equator is 40,075 kilometers. From one pole around to the other and back again, It I is 40,008 kilometers.
Origin There are many theories about the origin of universe and earth. Early theories were only imaginary and not based on scientific research. For example, Homer wrote that in the beginning,there was a mighty river encircling land and sea like a serpent. Laker, more scientific theories were put forward. Now it is scientifically belived that the earth is 4600 million years old (4.6 billion) our planet earth is one of the nine planets revolving round the sun.
The sun is one of billions of stars in the Milky Way Galaxy. This galaxy itself is one of billions of galaxies in the Universe. The Universe came into existence 12-13 billions years ago. No one can say for sure how the earth was formed, but the scientists agree on a likely sequence of events. The solar system (sun and planets etc.) was a cloud of gas and dust. Something,perhaps the shock waves from an exploding star nearby, caused the cloud to clumptogether. Thus, a huge, whirling disc of gas and dust was set in motion. Matter fell into the centre,became hotter and this core of energy became our Sun. Gradually, the fragments of dust spinning around the Sun, started to clump together. At first, they became small rocks, then became large boulders. Such huge boulders were known as planetesimals". Such planetesimals began to collide with other and eventually became the four rocky inner planets Mercury, Venus, Earth and Mars. The 'gas giants' Jupiter, Saturn, Uranus and Neptune were also formed.
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