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Unit: Life on Earth Topic 1: Understanding our Universe

Unit: Life on Earth Topic 1: Understanding our Universe. Biology in Focus, Preliminary Course Glenda Childrawi and Stephanie Hollis. Introduction .

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Unit: Life on Earth Topic 1: Understanding our Universe

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  1. Unit: Life on EarthTopic 1: Understanding our Universe Biology in Focus, Preliminary Course Glenda Childrawi and Stephanie Hollis

  2. Introduction In order to fully understand life on Earth, we first must first understand a little bit about the formation of the universe, our solar system and ultimately our planet Earth. You would have studies this in year 9 and 10 but we’ll quickly review now. map.gsfc.nasa.gov

  3. The Universe The universe includes all of space and all of the known matter and energy. This includes millions of galaxies and the stars within. Galaxies can contain up to 100000 million stars!! Where did all this come from???

  4. The Universe Scientist currently believe that the Universe started as a Big Bang and is still expanding away from a central group of galaxies. They believe happened between 15-20 billion years ago (BYA).

  5. The Universe Galaxies are the largest structures in the Universe. They are made from stars, gas and dust and are named according to shape. What galaxy do we live in?

  6. The Universe Looking at the night sky, you can see the Milky Way. It’s the part of the sky most densely populated by bright objects. This band of stars is the disc of our spiral galaxy.

  7. The Universe A solar system lies within a galaxy and is composed of planets, asteroids, comets and other objects that orbit a star or stars.

  8. The Universe A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity.

  9. The Formation of our Solar System The creation of Earth is interlinked with the creation of our solar system. They began forming at the same time as a result of the same forces about 4.6 billion Years ago.

  10. The Formation of our Solar System A large cloud of dust and gas (nebula) began to collapse onto itself. It is believed that this collapse may have been triggered by a shockwave from a supernova nearby. Video Nebula Supernova

  11. The Formation of our Solar System As the pressure caused by the collapse increased, the central sphere became very hot and started to glow forming a protostar. A wide disk formed around it’s equator.

  12. The Formation of our Solar System Due to gravity the nebula continued to collapse into a individual globular bodies and began to rotate. The Law of Conservation of Angular Momentum helps explain this phenomenon.

  13. The Formation of our Solar System Debris within the disk began to gather into large clumps by the process of accretion (The gathering together of small bodies into larger ones by gravity). This process is responsible for the initial formation of the planets. (We’ll come back to this in a second!)

  14. The Formation of our Solar System Depending on how close the planetesimals were to the sun, different materials would not be able to condense because of the heat and would be blown away by solar radiation.

  15. The Formation of our Solar System This would explain the rocky inner planets and gaseous outer planets of our solar system.

  16. Back to Earth The first billion years of Earth’s life the planet was a relatively cool and homogenous (the same, uniform) mass of silicon compounds, iron and magnesium. These materials would have been distributed evenly throughout Earth’s interior.

  17. Back to Earth As planet Earth grew in size and mass it’s gravity also increased attracting more and more meteorites and other objects floating around in the early formation of our solar system.

  18. Accretion Under the force of gravity, the materials began to build upon each other increasing temperature and pressure. As temperature increased, rocks became molten and the process of differentiation began.

  19. Earth’s Interior The Early differentiation of materials is preserved in the Earth’s layers today. But how do we know this? Scientists haven’t been able to drill through the Earth’s crust…..

  20. Earth’s Interior Scientists have been able to make inferences about Earth’s interior by studying the way earthquake waves (seismic waves) travel through Earth’s interior and by studying meteorites that have preserved the original ingredients of the solar system.

  21. Earth’s Interior The internal structure of materials within the Earth is layered according to variations in density. The densest materials sink to the centre and form the core while the less dense materials float to the surface and form the crust.

  22. Earth’s Interior Iron and nickel are the densest of the materials found on Earth and are therefore believed to be the main elements of the core.

  23. Earth’s Interior Pyroxene and olivine are less dense and can be found in the layer above the core.

  24. Earth’s Interior Granite and sandstone are the least dense and are found above the other two layers and form the outer layers which includes the crust.

  25. Homework None! Enjoy the free time!

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