1. The Origin of the Earth The Origin of the Earth

2. Explanations About the Earth’s Origins Throughout history there has been numerous ideas, theories, legends, and explanations about the origins of the Earth Throughout history there has been numerous ideas, theories, legends, and explanations about the origins of the Earth As time and technology advances we are becoming more knowledgeable about our Earth and its origins. As time and technology advances we are becoming more knowledgeable about our Earth and its origins.

3. Meteorites: Key to Earth’s Age A not very obvious, but very important source of information about the Earth is meteorites- especially Chondrite meteorites A not very obvious, but very important source of information about the Earth is meteorites- especially Chondrite meteorites

4. Chondrite Meteorites: Key to Earth’s Age Most meteorites that are recovered on Earth are chondrites: ~86% of witnessed falls are chondrites Most meteorites that are recovered on Earth are chondrites: ~86% of witnessed falls are chondrites Formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids. Formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids. Chondrites are the enigmatic chondrules, millimeter-sized objects that originated as freely floating, molten or partially molten droplets in space Chondrites are the enigmatic chondrules, millimeter-sized objects that originated as freely floating, molten or partially molten droplets in space Chondrites also contain refractory inclusions which are among the oldest objects to form in the solar system Chondrites also contain refractory inclusions which are among the oldest objects to form in the solar system

6. Chondrite Meteorites: Key to Earth’s Age Analyses of these granules reveal they contain water and other volatile elements that have turned into gases at relatively low temps. Analyses of these granules reveal they contain water and other volatile elements that have turned into gases at relatively low temps. This tells us that meteorites have not melted since their formation This tells us that meteorites have not melted since their formation Measuring meteorites for radioactive decay indicates that they formed up to 4.6 billion years ago- the date of the Earth’s beginning Measuring meteorites for radioactive decay indicates that they formed up to 4.6 billion years ago- the date of the Earth’s beginning

7. The Formation of the Earth These new data reveal that the early histories of the inner planets in the solar system are complex and involve processes no longer observed. Evidence of these processes has been preserved in Mars, while it has been erased in Earth. So Mars is probably the best opportunity to understand how Earth formed. These new data reveal that the early histories of the inner planets in the solar system are complex and involve processes no longer observed. Evidence of these processes has been preserved in Mars, while it has been erased in Earth. So Mars is probably the best opportunity to understand how Earth formed.

8. Earth Gains Mass and Loses Atmosphere Earth is formed through accretion of dust and gases Earth is formed through accretion of dust and gases After solar wind swept away the remaining interplanetary dust and gases, accretion continued as meteorites and other matter collided with the earth adding to its mass After solar wind swept away the remaining interplanetary dust and gases, accretion continued as meteorites and other matter collided with the earth adding to its mass

9. Earth Gains Mass and Loses Atmosphere As the Earth grew in size its gravitational attraction increased As the Earth grew in size its gravitational attraction increased This pulled in even more meteorites This pulled in even more meteorites It is thought that the Earth approached its current size with in a few million years of the collapse of the nebula (big bang) It is thought that the Earth approached its current size with in a few million years of the collapse of the nebula (big bang)

11. Differentiation: Forming an Iron Core Figure 2.10 in your text book shows the series of events that led to the major changes in the Earth after ignition of solar furnaces Figure 2.10 in your text book shows the series of events that led to the major changes in the Earth after ignition of solar furnaces The melting interior is a result from the accumulated heat of gravitational energy The melting interior is a result from the accumulated heat of gravitational energy Once the interior melted the heavier elements of iron and nickel were attracted inward to form our dense core. Once the interior melted the heavier elements of iron and nickel were attracted inward to form our dense core. The lighter compounds such as magnesium and silicon moved outward to create a crust The lighter compounds such as magnesium and silicon moved outward to create a crust

13. Differentiation: Forming an Iron Core Differentiation of this type, which lead to the layers within the Earth’s interior, could only occur in a liquid or semi-liquid. Differentiation of this type, which lead to the layers within the Earth’s interior, could only occur in a liquid or semi-liquid. Differentiation Examples (driving forces) Differentiation Examples (driving forces) Oil and water Oil and water Candle in the wind Candle in the wind Mercury and water Mercury and water Mentos and Cola Mentos and Cola

14. What is the Center of the Earth? One of the most distinctive features of the earth's interior is how it seems to be layered by density, with the heaviest stuff in the center, and the lightest material at the surface. One of the most distinctive features of the earth's interior is how it seems to be layered by density, with the heaviest stuff in the center, and the lightest material at the surface. In fact, the earth probably looks a lot like a hard boiled egg if you could cut it open. In fact, the earth probably looks a lot like a hard boiled egg if you could cut it open. The yellow stuff in the center (the yolk) relates to what we call the core. The yellow stuff in the center (the yolk) relates to what we call the core. The egg's shell is like the earth's crust - a thin veneer of rigid, low density material at the surface. The egg's shell is like the earth's crust - a thin veneer of rigid, low density material at the surface. The white stuff in between is like the earth's mantle - the largest layer which, in the case of the earth, is of medium density The white stuff in between is like the earth's mantle - the largest layer which, in the case of the earth, is of medium density

16. Second Atmosphere A second major event in the Earth’s history was the formation of a new atmosphere replacing the early one, which had been removed by solar wind that accompanied the ignition of the sun’s furnace. A second major event in the Earth’s history was the formation of a new atmosphere replacing the early one, which had been removed by solar wind that accompanied the ignition of the sun’s furnace. The gases made up this new atmosphere cam from the melting of the rocks in the Earth’s Mantle and Crust. The gases made up this new atmosphere cam from the melting of the rocks in the Earth’s Mantle and Crust.

17. Second Atmosphere The volcanic eruptions released volatile elements and compounds including: methane, water vapor, ammonia, sulphur dioxide, hydrogen, and carbon dioxide. The volcanic eruptions released volatile elements and compounds including: methane, water vapor, ammonia, sulphur dioxide, hydrogen, and carbon dioxide. By this time the Earth’s crust cooled enough to become solid and temperatures were between freezing and boiling water By this time the Earth’s crust cooled enough to become solid and temperatures were between freezing and boiling water The water vapors in the early atmosphere converted to liquid and fell like rain- the water collected to create the unique features of our oceans The water vapors in the early atmosphere converted to liquid and fell like rain- the water collected to create the unique features of our oceans

19. The Arrival of Life After the various process stated previously Earth was in a condition to sustain life After the various process stated previously Earth was in a condition to sustain life The earliest signs of life on Earth are in rocks 3.5-3.8 billion years ago The earliest signs of life on Earth are in rocks 3.5-3.8 billion years ago

20. The Arrival of Life Early life forms had to adapt to life with no oxygen (or little if any was present) Early life forms had to adapt to life with no oxygen (or little if any was present) Oceans provided the most favorable conditions to live Oceans provided the most favorable conditions to live According the evolutionary theory, species appeared that used the process of photosynthesis to create food from sunlight, carbon dioxide and other minerals. According the evolutionary theory, species appeared that used the process of photosynthesis to create food from sunlight, carbon dioxide and other minerals. These species are responsible for creating the third major change of the earth: an atmosphere with significant amount of oxygen These species are responsible for creating the third major change of the earth: an atmosphere with significant amount of oxygen

21. Critical Thinking Scientists from NASA's Johnson Space Center (JSC) and the Lunar and Planetary Institute and the University of California, Davis (UCD) has found that terrestrial planets such as the Earth and Mars may have remained molten in their early histories for tens of millions of years. The findings indicate that the two planets cooled slower than scientists thought and a mechanism to keep the planet interiors warm is required. Scientists from NASA's Johnson Space Center (JSC) and the Lunar and Planetary Institute and the University of California, Davis (UCD) has found that terrestrial planets such as the Earth and Mars may have remained molten in their early histories for tens of millions of years. The findings indicate that the two planets cooled slower than scientists thought and a mechanism to keep the planet interiors warm is required.

22. Critical Thinking What ideas/tools/technologies could we implement to ensure that the interior of our planet stays warm? What ideas/tools/technologies could we implement to ensure that the interior of our planet stays warm? What effects does a cooling planet have on Earth (land formations, water, etc) and its inhabitants? What effects does a cooling planet have on Earth (land formations, water, etc) and its inhabitants?

23. Homework/Further Explorations Complete Questions 14a, 14b, 15a, 15b, and 16 on page 33 in your textbook. Complete Questions 14a, 14b, 15a, 15b, and 16 on page 33 in your textbook. Please use complete sentences when answering the questions Please use complete sentences when answering the questions Questions are due for tomorrow, and will be discussed at that time Questions are due for tomorrow, and will be discussed at that time