Habitable Zone Notes

1. Habitable Zone Notes “Life in the Goldilocks Zone”

2. Necessary Components for Life: 1. Gravity • The sun’s large mass causes a gravitational pull on all planets. The smaller the mass of the planet, the stronger the gravitational pull and thus the closer the planet is to the sun. • Earth’s mass enables it to be the perfect distance from the sun. Earth is the only planet in the habitable zone: area the space that has ideal conditions to enable life to exist. • In our solar system, the habitable zone extends from after Venus to just before Mars, so Earth is the only planet within it.

3. READ ONLY The habitable zone is the only spot in space where life can exist because it meets all 8 necessary components for life. = Just right = Too cold = Too hot Earth The 3rd planet from the sun

4. Necessary Components for Life: 2. Energy Source: The Sun • The sun is the vital energy source for life on our planet. Producers get their energy from the sun through photosynthesis, fueling the food web on Earth. Producers are the start of the food web

5. Necessary Components for Life: 3. Temperature • The sun radiates thermal energy that is absorbed by Earth. • Other factors that increase the heat of Earth to a temperature that can sustain life include: • Geothermal Energy from Earth’s Molten Iron Core • The Greenhouse Effect • Plate Tectonics: Divergent, Convergent, and Transform plate boundaries Convection Currents provide geothermal energy

6. Necessary Components for Life: 4. Green House Heating • Large amounts of green house gases, such as Carbon Dioxide, reflect that heat back to the surface of a planet and warm it. • The ability of a planet to retain it’s gases, depends on the composition of the atmosphere and the strength of the planet’s gravity. READ ONLY: Greenhouse gases are a positive until we over-increase the amount of them. Burning fossil fuels release pollutants into the air and increases the amount of carbon dioxide. The more carbon dioxide in the air, the warmer the planet will get. Since plants convert CO2 into O2 through photosynthesis, removing plant life will also increase the amount of CO2 in the atmosphere.

7. READ ONLY Greenhouse Effect aka Global Warming The greenhouse effect is a process by which thermal radiation from the sun is absorbed by atmospheric greenhouse gases (Carbon Dioxide, Water Vapor, and Methane), and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases The primary source of Greenhouse gases are from the burning of fossil fuels (coal, oil, and natural gas). Volcanic eruptions and decomposition in landfills also increase greenhouse gases.

8. READ ONLY

9. READ ONLY Advantages of Greenhouse Gases The gases slow down the rate that heat leaves the Earth System Without greenhouse gases, the Earth would have freezing temperatures Disadvantages of Greenhouse Gases Increase of storms and hurricanes Increase in tropical diseases (malaria) Global warming Melting of Polar Ice Caps Rising Sea Levels Flooding of Costal Areas

10. Necessary Components for Life: 5. Plate Tectonics • Plate Tectonics create volcanoes release the greenhouse gas, Carbon dioxide, into the air which causes a planet’s temperature to rise. • Early Earth had many Volcanoes, putting large amounts of Carbon dioxide into the atmosphere. • Plate tectonics • regulate the surface temperature of the planet • create a magnetic field -- Van Allen Radiation Shield-- to block the planet from the deadly solar winds • create dry land on a water-covered world

11. READ ONLY Earth’s magnetic field Van Allen Radiation Shield

12. Necessary Components for Life: 6. Composition of the Atmosphere • Earth’s gravity is strong enough to retain it’s atmosphere. Earth’s atmosphere has changed over time. • Today, Earth’s atmosphere consists of • 78% Nitrogen • 21% Oxygen • 0-.4% Water Vapor • .93% Argon • .03% Carbon dioxide • Trace amounts of Neon, Helium, Methane, and Hydrogen

13. Necessary Components for Life: 7. Mass • Planets must have the ideal mass to promote the existence of life. • More mass= stronger pull of gravity • A planet smaller than Mars could not hold on to it’s atmosphere, over time the gases would diffuse into space. • A planet with a very large mass will hold onto any gases surrounding it, and become a densely clouded like the outer planets of our solar system and are not suitable for life.

14. Necessary Components for Life: 8. Presence of Water • Liquid water is directly linked to the existence of life. • In order for LIQUID water to exist, warm temperatures are essential. • Temperatures needed for water to be a liquid: • 32-212⁰F or 0-100⁰C

15. HIGHLIGHT BOLD BOX IN Habitable Zone Notes To make each of the 8 necessary components stand out in your notes, pick one of the following: Necessary Components for Life: 1. Gravity • The sun’s large mass causes a gravitational pull on all planets. The smaller the mass of the planet, the stronger the gravitational pull and thus the closer the planet is to the sun. • Earth’s mass enables it to be the perfect distance from the sun. Earth is the only planet in the habitable zone: area the space that has ideal conditions to enable life to exist. • In our solar system, the habitable zone extends from after Venus to just before Mars, so Earth is the only planet within it. EXAMPLE 2. Energy Source: The Sun The sun is the vital energy source for life on our planet. Producers get their energy from the sun through photosynthesis, fueling the food web on Earth.

16. Assignment: Sketch the picture of the Habitable Zone shown below. Explainwhat this term means (in your own words) andwhy this is also referred to as the “Goldilocks Zone” USE the 8 Necessary Components for Life to support your answer.