1. THE UNIVERSE
Part 3: Earth and Life

2. Earth & Life
Our solar system was once a large cloud of gases and heavy metals. This suggests that our region of space was once the host of another star that underwent a supernova. Gradually, over time, these gases and heavy metals began to collide and form a protostar. This protostar would eventually become our Sun, paving the way for the formation of our solar system

3. Earth & Life The solar system forms in four stages:
The gas and metal cloud begins to collapse and spin
The speed of rotation allows some material to collide and form a protoplanetary disk
The material in this protoplanetary disk begins to clump together and form the planets
The protostar undergoes the transformation into the sun as gravitational force increases

4. Earth & Life
Not all planets in our solar system are the same structurally. We place the planets into two classes:
Rocky Planets
Gas Giants

5. Earth & Life
Rocky planets, true to their name, consist of a series of rocky layers.
The core of these planets is very dense due to the effects of…………… pulling in heavier metals.
Gradually, the outer layers become less dense until you reach the outer mantle and crust.
The mantle is composed of light silicon based rocks, while the crust is composed of lighter elements such as sodium, aluminium and magnesium.

6. Earth & Life
Gas Giants differ from rocky planets in that their layers are primarily composed of gaseous and liquid gas elements such as hydrogen and helium.
The core of these planets is very dense, composed of some rocky elements and metallic hydrogen
Large amounts of liquid hydrogen and helium compose the middle layer, while the outer layer is composed of gaseous hydrogen and helium.

7. Interestingly, our planet is perfectly tailored to supporting human life…

8. Earth & Life But how did life first begin on our planet?
Several different theories for the origins on life have been put forward…
Abiogenesis
Panspermia

9. Earth & Life
Abiogenesis is the process where, under prehistoric conditions, elements such as hydrogen, carbon and oxygen were subjected to electrical voltages in the form of lightning to generate the building blocks of life. These included Amino Acids and Carbohydrates.

10. Earth & Life
Panspermia is the theory that life on our planet developed from organisms that ‘arrived’ here on top of asteroids. These organisms, also known as tardigrades, were extremely resilient, allowing them to survive the vacuum of space.
Eventually, these organisms would evolve to give those that we know today

11. Earth & Life
The atmosphere of the earth is perfectly suited for sustaining life
The earth’s orbit around the sun places it in a habitable zone
The earths tides allowed prehistoric organisms to adapt to living on land
Important elements in our atmosphere help to drive metabolic reactions in organisms