1. How Earth Became Habitable Habitability

2. Obviously…… The planet has to form first….check your notes on planet formation.

3. Conditions necessary for Habitability A planet or planetary satellite is said to be habitable if it can sustain life that began there or was brought there. (NASA) The first thing astronomers look for is liquid water. The planet cannot be too hot or too cold, it must be just right (goldilocks zone) Generally, we believe there must be an atmosphere or another method to protect life from harmful radiation

4. Habitable zone (Goldilocks)

5. Habitability in our Solar System The only known habitable planet in our solar system is planet Earth. Current research is looking at the moons of Jupiter and Saturn as possible habitable locations. Europa

6. Habitability outside our Solar System With new technology we have been able to discover over 450 extra-solar planets (planets outside our solar system) So far most of what we discovered are huge gas giants larger than Saturn. These are unlikely to support life Statistically speaking in our Galaxy (the milky way) there are estimated 10,000,000,000 Earth-like planets

8. Earth’s First Atmosphere The creation of the Earth through collisions initially left the surface of the planet molten Earth slowly cooled and formed a solid crust The gasses that were originally dissolved in the molten rocks were released Earth’s first atmosphere resembled the gasses from volcanic eruptions. The first atmosphere was composed of Water vapor, carbon dioxide, nitrogen and several trace gasses. No oxygen!

9. Evolution of Earth’s Atmosphere As the planet continued to cool the water vapor in the atmosphere fell as rain Rain evaporated before or upon reaching the surface Evaporation increased the rate of cooling Eventually water accumulated in the low areas creating oceans and seas Most of the Carbon dioxide was dissolved in the oceans The remaining atmosphere was Nitrogen rich

10. Continued Evolution Eventually primitive organisms started to use photosynthesis to generate energy This produced a byproduct of oxygen gas Initially the oxygen gas would attach to metals (iron oxide, aluminum oxide etc…) Eventually the oxygen collected in the atmosphere (2.5 billion years ago)

11. Earth’s Evolving Atmosphere

12. Composition 79% N 2 Nitrogen gas 20% O 2 Oxygen gas.93% Argon an inert (Noble) gas.039% Carbon Dioxide (CO 2 ) Although it only makes a small percent it has large impacts globally.031% other gasses

13. Your Project: Poster Fun You and your partner will be researching an object in the solar system and making a poster presenting its possible habitability Main Points: Compare your object to earth Positives (assets) Negatives (challenges) How to overcome the challenges (What would daily life be like on your object? Travel time there and back?)

14. Comparing to earth Gravity Atmosphere Surface conditions (climate, temperature) Resources

15. Positives should include What requirements for habitability are present? What reasons do you have for going there? Money Minerals Scientific Purposes

16. Negatives Drawbacks to living there What doesn’t your object have? What would need to be shipped? Costs

17. Overcoming Challenges Living Structures Technology Daily Life Transportation Food Water Air Protection from radiation Temperature control There and back again

18. Topic Choices MercuryVenusLuna MarsCeresIo EuropaCallistoGanymede TitanIapetusMiranda OberonTritonVesta HaumeaSedna

19. Grading Rubric Points543210 Ontime completion Tues. Beginning of class Tues. in classTues. end of the day Wed. before school Wed. beginning of class After that Earth Comparison Superior Completion All topics Covered Missing one topic/Badly done Missing two topics/Badly done Missing Three/Badly done Didn’t Do ProsSuperior Completion All topics Covered Missing one topic/Badly done Missing two topics/Badly done Missing Three/Badly done Didn’t Do ConsSuperior Completion All topics Covered Missing one topic/Badly done Missing two topics/Badly done Missing Three/Badly done Didn’t Do Overcoming Challenges (X 2) Superior Completion All topics Covered Missing one topic/Badly done Missing two topics/Badly done Missing Three/Badly done Didn’t Do Bibliography3 or more citations/M LA or APA 3 or more, bad format 2 proper format 2 bad format1 good format 1Bad format or not done