jasperhoek

[jasperhoek]

Big History Project

The solar system has been around for a really long time. I am gonna tell you all about this solar system in this blog post. In the subject Big History, we work with Thresholds. A Threshold is an important event in our entire history. So this is Threshold 4: Our solar system and the Earth.

So first we must ask ourselves this: How did the solar system come to be? The answer is not simple, but I am already telling you, it was really messy. So basically, we started with two elements, which are hydrogen and helium. These elements help make stars, and when a big star collapses you get supernovae. These supernovae collapsed a cloud of matter under the pressure of gravity and seeded that cloud with different materials. The cloud flattened and begun to spin so much, it became a protoplanetary disk. The centre of the disk became hotter and hotter and fusion began to take place and the Sun was formed.

Someone tossing and spinning pizza dough, a representation of the formation of a protoplanetary disk by flattening and spinning the cloud of matter, just like with pizza dough. Source: huffpost.com

But what about all the planets? 99.9% of all materials of the protoplanetary disk went into the Sun. The planets are made out of the rest. The gas giants formed because the heat from the Sun drove away, so the gasses and they collected further out in the solar system to form the gassy planets. That took away 99% of that 0.01% that was left, so the other planets were made out of that. Closer to the Sun you got small rocks orbiting around the Sun. These rocks developed a gravitational pull which pulled in different materials eventually creating planets. This process is called accretion.

Let’s go somewhere that hits closer to home: the Earth. The Earth is also a product of accretion, and as we know, the only planet with living beings on it. But was the Earth always habitable? No. There was too much radioactivity, it was volcanic, there was no atmosphere so it would get very warm and meteorites and other smaller celestial bodies would hit the surface, and last of all, there was no oxygen. So how did Earth become habitable? The answer is pretty simple. Because the heat of the supernovae and accretion, the Earth kind of formed layers where heavier metals like iron and nickel sunk to the bottom. And because they are irons, they began to develop a magnetic field. This field is very important and it kept in oxygen. Then, over the next like 3 billion years, the Earth cooled down and was a liveable place.

So what does this have to do with Thresholds 3 and 5? Well, new elements were formed due to the supernovae. We needed these stars to collapse in order to get the clouds of matter to be seeded with new materials so stars could form. Those are the Goldilocks conditions for Threshold 3. These Goldilocks conditions are nearly perfect conditions to form new complexity. The Goldilocks conditions for Threshold 4 for example, are gravity and accretion, without those, we could not have our solar system. As for Threshold 5, the new complexity is biodiversity. This biodiversity would never even have taken place if it wasn’t for the development of our solar system. There was life possible now and plants could grow. The new atmosphere could hold the oxygen in the plants created. Mini cells started to grow which would eventually develop into us. So this is how Thresholds 3 and 5 are related to Threshold 4.