1. What is need for life to exist?

2. Liquid Water Transports and delivers dissolved chemicals to living organisms Some type of cycle to transport the H 2 O l

3. Energy All life requires energy Light Energy – Solar Energy (Sunlight) Chemical Energy – Break down of complex compounds into simpler ones = small amount of energy Organic (carbon containing) Inorganic – Sulfide and manganese compounds

4. Nutrients The raw materials organisms need to construct and maintain their bodies. All planets and moon have about the same make-up, but vary in amounts and availability of different chemical compounds.

5. Right Temperature 5° F to 239° F = life Creates H 2 O l Habitable Zone – Comfortable temp. surrounding every star – Hotter the star the larger the area – Our Solar System area includes :Venus, Earth, and Mars

6. Habitable Zone astro.psu.edu astrobio.net

7. Atmosphere Block UV rays Traps heat: greenhouse effect Magnetic field helps protect Provides some nutrients – Nitrogen: use to make proteins – Carbon: use to make carbohydrates and fats (food) How thick the atmosphere should be is determined by how far away it is from the Sun

8. Comparison activity PlanetLiquid Water EnergyNutrientsTemp.Atmosphere Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Eris Titan Callisto

9. Moon and Mercury O Lack O H 2 O l O Atmosphere O Magnetic field O Bombardment by: O UV rays O Meteoroids O Cosmic rays

10. Venus O Too much protective atmosphere O Dense, dry, scorching hot atmospheric blanket = in life

11. Jovian Plants (Gas Giants) O No solid surfaces

12. Dwarf Planets O Too cold

13. Titan and Europa O Titan: O Atmosphere of methane, ammonia, and N 2 ; geological activity; and possibly H 2 O l hydrocarbon lakes or oceans on tis surface = life? O Europa: O H 2 O l under the icy surface = life? Titan Europa

14. Mars O VIDEO

15. Life Out There? On average, for every 10 planetary systems there is one habitable planet that exist in our Galaxy. Single F, G, and K types stars are the best candidates for life

16. H-R Diagram F, G and K best stars for life

17. To find life… Space probes – 50km/s is the current fastest speed Electromagnetic radiation – Cheap communication