1. Do First Questions: 1. Why is the Big Bang considered an expansion and not an explosion?

2. Agenda 1.Formation of the Earth Notes 2.Spheres of the Earth Notes 3.Spheres of the Earth Practice

3. Earth’s History Big Bang (universe) Nebular Hypothesis (our solar system) Formation of the Earth (4.5 billions of years ago)

4. Step 1 More than 4 billion years ago, our sun was young and much hotter than it is now. The planets that we are familiar with today were still just a swirling cloud of rock and ice.

5. Step 2 Rock and ice particles swirling around outer space collided. As these violent, massive, high velocity collisions occurred, the material built up to begin to form our planet

6. Step 3 The collisions of rock that formed our Earth created so much heat and energy that they were like explosions. Our planet was scorching hot and melted rock.

7. Step 4 A large object, as big as Mars, struck our planet while it was still forming. It made a dent in the surface of baby Earth the size of an ocean and most of the object was swallowed up in the bottomless magma ocean it created. The collision also flung a small amount of rock into orbit. This debris quickly gathered itself into a ball, creating our moon.

8. Step 5 Even when the Earth’s surface cooled it remained an alien world for the next 700 million years. Magma continuously erupted out of the surface. Rafts of solid rock drifted in the magma.

9. Step 6 Gases hissed from the cooling rock on Earth’s surface—carbon dioxide, nitrogen, water vapor, and others—covering the planet in a poisonous atmosphere.

10. Step 7 As the temperature dropped on baby Earth clouds began to form and rain fell. The rain cooled the hot surface into solid rock. Some of the water pooled into bodies of water.

11. Step 8 Asteroids stopped hitting Earth and the sun shone. Oceans became deeper. About that time, single-celled, blue-green bacteria developed in the oceans. By the trillions, these microscopic organisms transformed the planet. They captured the energy of the sun to make food. Little by little they turned the poisonous atmosphere into breathable air.

12. Step 9 Today, billions of years later, heat left over from the planet’s formation still bursts out in volcanic eruptions. In some places, the same algae organisms still exist that first lived on Earth. These are the few clues we have to imagine what our Earth was like in the very beginning.

13. A brief history of the Earth 1.Planet formation 2.Moon formation 3.Land formation 4.Ocean formation 5.First Organisms, Cyanobacteria & Oxygen formation

14. Planet Formation Through the gravitational pull of large objects and rocks colliding into each other the planet was formed. Dense material moved to the center and less dense material stayed near the surface creating the layers of the Earth.

15. Moon formation Through a large object the size of Mars hitting Earth and breaking off pieces of the Earth’s surface that became the moon

16. Land formation Through the cooling of the Earth which allowed the Earth’s molten crust to harden.

17. Ocean formation Through many meteorites carrying water hitting the Earth and water vapor gas being released from the surface of the Earth. It rained for millions of years to create the deep oceans.

18. First Organisms, Cyanobacteria & Oxygen formation Life began in the ocean. The first photosynthetic organisms, cyanobacteria, produced enough oxygen to change the poisonous atmosphere to one that could support more life.

19. Quick Check Without looking at your notes, see if you can place the below steps in order: 1. Land formation 2. Planet formation 3. Life, Cyanobacteria, and Oxygen formation 4. Moon formation 5. Ocean formation

20. Spheres of the Earth Everything in Earth's system can be placed into one of four major subsystems: land, water, living things, or air. These four subsystems are called "spheres.“ Specifically, they are the – "geosphere" (land), – "hydrosphere" (water), – "biosphere" (living things) – "atmosphere" (air) Spheres can occupy the same space

21. Spheres of the Earth

22. 1. Hydrosphere Ocean is the most prominent feature of the hydrosphere. - Covers nearly 71% of Earth's surface Also includes fresh water found in streams, lakes, and glaciers, as well as that found underground

23. 2. Atmosphere Body of air surrounding our planet Most of it is close to the Earth’s surface 3. Biosphere Includes all life Spheres of the Earth Majority of it is nitrogen (79%), some is oxygen (21%), the rest is other gases

24. Spheres of the Earth 4. Geosphere Solid parts of the Earth Includes the interior of the Earth

25. Geosphere

26. Which do you see?

27. Practice Fill in the back of the sheet Make sure you color the spheres When done, tell the teacher to stamp your paper

28. DYL 1.Which step in the formation of Earth was ultimately necessary for humans to develop? 2.Which sphere includes ponds, rivers, and puddles?