1. Life

2. What makes something alive React to environment React to environment Grow by taking in nourishment Grow by taking in nourishment Can reproduce Can reproduce Capacity for genetic change (evolution) Capacity for genetic change (evolution)

3. Why Earth? What make Earth unique from other places? Liquid water Liquid water Energy source Energy source Presence of the elements that are necessary for relevant biochemical reactions (metabolism and reproduction)--C, H, O, N, S & P Presence of the elements that are necessary for relevant biochemical reactions (metabolism and reproduction)--C, H, O, N, S & P Atmosphere Atmosphere Stable environment (few impacts, Stable environment (few impacts, Location, Location, Location Location, Location, Location etc.) etc.)

4. Why is liquid water so important 1. No life on Earth is possible without it. 1. No life on Earth is possible without it. 2. It is a solvent for most molecules. 2. It is a solvent for most molecules. 3. Liquid at a large range of temperatures (0-100°C)--the upper temp limit is closest to the highest temp at which complicated organic molecules can survive 3. Liquid at a large range of temperatures (0-100°C)--the upper temp limit is closest to the highest temp at which complicated organic molecules can survive Ammonia, Methane and Ethane Ammonia, Methane and Ethane are possible alternates to water are possible alternates to water

5. Energy Sunlight photosynthesis Sunlight photosynthesis Lightning or electrical discharge (using organic molecules made by the lightning) Lightning or electrical discharge (using organic molecules made by the lightning) Heat from hydrothermal vents (organics created by chemical reactions) Heat from hydrothermal vents (organics created by chemical reactions) Fermentation Fermentation Oxidation (O2, H gas or CH4 obtained by interaction with crust) Oxidation (O2, H gas or CH4 obtained by interaction with crust)

6. Stability and Atmosphere Life needs a stable environment to develop and survive. Life needs a stable environment to develop and survive. Impact rate must decline significantly from early numbers-- in our own solar system the gravitational pull of outer planets such as Jupiter and Saturn have acted as comet/meteorite blockers. Impact rate must decline significantly from early numbers-- in our own solar system the gravitational pull of outer planets such as Jupiter and Saturn have acted as comet/meteorite blockers. Protection from UV radiation Protection from UV radiation Presently ozone (O3) protects the Earth. On early Earth, a very thick atmosphere would have helped to protect life plus living in a shallow layer of dirt or water would help. Another possibility would be a subsurface ocean, such as might exist on Jupiter's moon Europa Presently ozone (O3) protects the Earth. On early Earth, a very thick atmosphere would have helped to protect life plus living in a shallow layer of dirt or water would help. Another possibility would be a subsurface ocean, such as might exist on Jupiter's moon Europa

7. Habitability Zone

8. Ammonia World Liquid ammonia based life. Temp -40°C-- 70°C. This kind of life would live in a large ocean, heated to these temperatures by a greenhouse CO2 atmosphere. Liquid ammonia based life. Temp -40°C-- 70°C. This kind of life would live in a large ocean, heated to these temperatures by a greenhouse CO2 atmosphere.

9. Vent World Hyperthermophiles that live in the bottom of an H2O ocean on a planet without a Jupiter or Saturn to protect against impacts. Hyperthermophiles that live in the bottom of an H2O ocean on a planet without a Jupiter or Saturn to protect against impacts.

10. Frozen World Bacteria living inside rocks that are composed of mainly solid CO2 and H2O. Sunlight melts the H2O on the dark rocks allowing chemical reactions to take place. Average temperature is -30°C. Bacteria living inside rocks that are composed of mainly solid CO2 and H2O. Sunlight melts the H2O on the dark rocks allowing chemical reactions to take place. Average temperature is -30°C.

11. Ice Ocean World H2O based life that live under 1 mile of ice in a large liquid ocean. The ocean is heated due to tidal dissapation of a moon. The planet is 2 Jupiter masses in size. H2O based life that live under 1 mile of ice in a large liquid ocean. The ocean is heated due to tidal dissapation of a moon. The planet is 2 Jupiter masses in size.

12. Lightning World A massive Jupiter sized planet at temperatures ~300°K. Large clouds of H2O provide liquid H2O (rain). There is no solid surface. Lots of lightning. A massive Jupiter sized planet at temperatures ~300°K. Large clouds of H2O provide liquid H2O (rain). There is no solid surface. Lots of lightning.