How was the earth formed?
The earth, along with the sun and the remaining planets of our solar system, originated around 4.8 billion years ago from dust particles, which agglomerated gradually. At that time, the young earth was bombarded by countless meteorites from space. The earth’s interior was molten and volcanoes erupted constantly. But over millions of years, the earth’s surface cooled down. Around 3.8 billion years ago, The temperature decreased at about 100 degree celcius. And the earth’s crust slowly started becoming solid. At this time the gaseous cover on the earth was mostly made up of water vapour.
Why did life develop on the earth?
The origin of life on the earth is a fortunate series of events. The earth’s distance from the sun was such that its atmosphere and surface cooled down to a moderate level. Liquid water-and not just water vapour also formed, and it did not freeze as the sun was not too far away. The cooling of the earth gave rise to a kind of ‘primordial ocean‘. The action of the UV rays of the sun, the lightning flashes produced by storms, and the countless volcanic eruptions gave rise to new complex chemical compounds. About 4 billion years ago, he first molecules appeared, from which the first unicellular organisms were formed.
where does the oxygen we breath come from?
Gaseous oxygen was created on the earth about 3.8 billion years ago. At that time, the UV light of the sun decomposed the water vapour molecules present in the atmosphere, And released oxygen and hydrogen.
But a major part of the oxygen immediately reacted with other substances, so that it was no longer available in the atmosphere as gas. Oxygen was also produced by the seas, where the ‘blue algae’ carried out photosynthesis. These bacteria converted sunlight and carbon dioxide was released as a ‘waste product’, which accumulated in the atmosphere. About one billion years ago, about one-twentieth(4%) of the atmosphere consisted of oxygen.