From Dust Cloud To Planet- Part 2

 

The millions of years of changing conditions, with one factor influencing the next, all leading to a chain of events eventually creating the perfect conditions for human life to thrive is indeed fascinating. Our home going from a cloud of dust to a gigantic rock wasn’t enough, and next came the atmosphere, oceans, and moon, to finally make our planet more recognizable as the one we know today.

Since Earth was initially just an accumulation of the materials flying around the solar system, there were all kinds of elements on its surface, including radioactive ones like uranium. Earth’s internal heat constantly increased due to the energy released by their radioactive decay. This caused the densest material like nickel and iron to sink to the centre of the planet, and the lighter materials to float near the top. Hence, the different layers of the planet that we know today- the core, mantle, and crust- were formed. The planet’s surface was hot and molten, covered with volcanoes. The eruptions released gases including water vapour, carbon dioxide, nitrogen, and methane. Over years, as the surface cooled and solidified, these gases created the early atmosphere of the planet. It’s ironic isn’t it, that volcanic eruptions are the ones that eventually created a habitable atmosphere? In due course, life emerged, and processes like photosynthesis led to the development of the oxygen-rich atmosphere we needed.

The oceans were formed thanks to the water vapor released through various unexpected sources, including comets, asteroids, and the same volcanic activity previously mentioned. We all know what happens to water vapor when temperatures reduce as the Earth’s surface cooled- it condenses. Behold, in came the oceans and seas of today. The comets and asteroids even brought water and other organic compounds and minerals directly to the surface with their impacts. These included carbon and nitrogen, essential for the development of life on Earth by providing the building blocks for the organic molecules that make up living organisms.

So now we have a planet with distinct layers, an atmosphere, some oceans, and the emergence of different life forms on the cooling surface. What are we missing? Our one and only moon. The most commonly accepted theory for the formation of the moon is called the Giant Impact Hypothesis. According to this hypothesis, around 4.5 billion years ago, a celestial object (about the size of Mars) collided with Earth. The collision caused a large amount of debris to be ejected into space. This debris eventually coalesced to form the Moon, which was just a molten mass of rock and metal at the time. Eventually it cooled, solidified, and formed different materials with the densest sinking to the core and the lightest forming the outer layers- you’ve learnt the pattern by now.

The processes that formed the Earth were complex and took place over a very long period of time, but the result is the beautiful and complex planet that we call home.