Habitability

1. Habitability How Earth Became Habitable

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% N2 Nitrogen gas • 20% O2 Oxygen gas • .93% Argon an inert (Noble) gas • .039% Carbon Dioxide (CO2) • 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 • Mercury Venus Luna • Mars Ceres Io • Europa Callisto Ganymede • Titan Iapetus Miranda • Oberon Triton Vesta • HaumeaSedna

19. Grading Rubric