1. Earth: The Goldilocks Planet. But what makes Earth such a special place?

2. The “Goldilocks” Planet The Story of Goldilocks and the Three Bears Once upon a time, there was a little girl named Goldilocks. She lived at the edge of the forest with her family. One morning, while she was picking flowers, Goldilocks wandered into the forest and lost her way. She was very frightened, but then she saw a friendly little cottage in the distance. The friendly little cottage belonged to three bears. One was a great big Papa Bear, one was a middle-sized Mama Bear, and one was a tiny little Baby Bear. That morning, the three bears decided to take a walk while their porridge – which tastes like oatmeal – was cooling. It was too hot to eat! Right as they left through the back door, Goldilocks came in through the front door very quietly. The first thing she saw and smelled was the sweet, steamy porridge. “I sure am hungry,” Goldilocks said. “I’ll just have one bite.” First, she tried a spoonful from Papa Bear’s great big bowl. “OW!” she yelled, “TOO HOT!” Next, she tried a spoonful from Mama Bear’s medium-sized bowl. “Brrrrr! TOO COLD!” she complained. Finally, Goldilocks tried a spoonful from Baby Bear’s tiny little bowl. “YUMMY!” she cried. “THIS IS JUST RIGHT!” Goldilocks ate the entire bowlful

3. The “Goldilocks” Zone Earth’s life-sustaining conditions are possible because of its position in the solar system It is not too hot and not too cold – if the Earth was any closer or further away from the Sun, the planet could not support life The key is the planet lies at a distance from it’s star that allows a temperature range that permits the existence of liquid water. BUT… what about Venus and Mars? They are still in what astronomers would consider the habitable zone, but no life. Why?

4. Earth’s life-sustaining conditions are possible because of its position in the solar system It is not too hot and not too cold – if the Earth was any closer or further away from the Sun, the planet could not support life The key is the planet lies at a distance from it’s star that allows a temperature range that permits the existence of liquid water. Bit… what about Venus and Mars. They are still in what astronomers would consider the habitable zone, but no life. Why? The “Goldilocks” Zone

5. BUT… what about Venus and Mars. They are still in what astronomers would consider the habitable zone, but no life. Why?

6. Atmosphere Consider the data table and graphs to the right. What are the most significant differences in the compositions of the atmospheres? What is different about Earth’s atmosphere?

8. Consider the diagram to the right. What is the relationship between carbon dioxide (CO 2 ) and temperature? If there is more the (CO 2 ) in the atmosphere what happens? If there is more (CO 2 ) trapped in the rocks what happens? How has the presence of life on earth effected the amount of carbon in the atmosphere and the temperature?

9. Layer of gases that surround the Earth about 80-100 km thick – very thin compared to size of Earth Helps maintain a consistent temperature by distributing heat around the planet Protects Earth from harmful U.V Radiation (ozone layer) Protects earth from collisions from debris from space (comets, meteors) Contains the optimal balance of gases that life forms on Earth need. Animal life needs O2, plants need CO2 Oxygen levels at 21% allow for great diversity of life, if they drop, animal life would not be possible, if it exceeds 25% most plants would be consumed by fire Oxygen is produced by plants and consumed by animals and the burning of plants and fossil fuels The Role of the Atmosphere

10. First water likely came from volcanic activity - water collected on the surface as Earth cooled. The water cycle moves water back and forth from the atmosphere to the surface. Biologists believe earth first began in the oceans – blue- green algae Oceans cover 2/3 of the Earth – absorbs heat and distributes it around the world and controls our weather patterns and climates Water helps distribute nutrients to plants and other organisms Life as we know it is water based. All life on earth are composed of one or more cells and cells are mostly water. Water is the metabolizing agent that allows plants and animals to dissolve minerals and nutrients to create energy The Importance of Water

11. VENUS EARTH Earth’s Magnetosphere What is the magnetosphere and why is it important? The Earth is a giant magnet. The magnetosphere is the magnetic field that surrounds the earth. It is important to life because it deflects harmful radiation and charged particles from the sun away from earth. Without this shield organisms would receive lethal doses of radiation and would be constantly blasted by charged particles The Aurora Borealis shown to the left is the result of the interaction between the magnetosphere and energy from the sun.

12. Earth’s rotation on its axis and orbit around the Sun determine how much heat any an area receives at any time of the years The rotation also helps distribute heat evenly around the planet by steering wind and ocean currents The Role of Earth’s Rotation and Revolution

13. What if Earth’s rotation was much slower or in the opposite direction like Venus? or What if the tilt in the axis was more than 23 degrees or less than 23 degrees. How would that affect conditions on earth? Would Earth still be habitable? 116d 18h 0m 23h 56m

14. The trapping of heat by the Earth’s atmospheres is known as the green house effect. It allows the overall temperature on earth to remain stable enough for life to exist The balances of greenhouse gases such as carbon dioxide, methane, and water vapor affect how much heat is trapped Plants play a significant role in creating a stable temperature by absorbing CO2 and releasing water vapor and oxygen by the processes of photosynthesis and transpiration What would happen is the amount greenhouse gases increased? What happens when humans cut down large areas of trees like rain forests. The Greenhouse Effect

15. The Role of Earth’s Gravity Earth’s gravitational field holds the atmosphere in place preventing oxygen, nitrogen, and carbon dioxide from escaping into space

16. Biosphere – The Carbon Cycle The movement of carbon from the atmosphere into plants, animals, and the soil and then back again Plants take carbon dioxide from the atmosphere to produce food through photosynthesis and release oxygen – animals breath oxygen and eat plants Dead animals and plants decay and return carbon to cycle Over production of carbon dioxide from factories and burning rainforests causes climate change

17. Microscopic bacteria live on the roots of certain plants known as legumes and converts nitrogen to ammonia and nitrates which the plant absorbs and converts to protein – food production Biosphere – Nitrogen Cycle