1. Chapter 8: Section 4 – Life in the Solar System

2. What is life? All living things have the following traits:
Made of cells
Use energy
Respond to their environment
Grow
Reproduce
Life on Earth is VERY diverse.

3. Exotic Life on Earth
Conditions on other planets and moons are very extreme
It does not seem that life could exist in these harsh environments
However, there are extreme environments on earth that support life
Yellowstone National Park – Bacteria live in pools of water that are boiling !

4. Exotic Life on Earth
Extremophile – an organism that lives in an environment that is very harsh; very hot; very cold; dark; salty; etc.
Volcanic Vents – locations on the ocean bottom without sunlight where water is heated by magma.
Crabs, shrimp, worms, and clams survive in water so scalding it would kill other creatures.

5. Exotic Life on Earth Other extremophiles:
Moss in Siberia can remain frozen and dormant for 40,000 years and come back to life
Three species of bacteria found in Mono Lake in California survive in an environment without light and oxygen and very high levels of lye and salt.

6. Can Life Exist on Other Worlds?
High temperatures, toxic gases, and exposure to solar radiation make life on other worlds unlikely BUT not impossible.
Extraterrestrial Life: Life on other worlds.
Scientists are currently searching for life on several moons and planets in our solar system.

7. Mars
During much of Earth’s history, the only living creatures were single celled bacteria.
Scientists are looking for proof that Mars currently or once had single-celled life.
A meteorite thought to have come from Mars, found in Antarctica, may have fossilized bacteria that are millions of years old.

8. Europa
Data from the Galileo space probe indicates that three of the Galilean Moons have ice covered oceans.
Europa’s ocean may be 25 m below its icy surface.
The pull of Jupiter’s gravity on Europa may even keep this water warm.
If life is found at the bottom of Earth’s oceans where there is no sunlight, then life might too exist on Europa.
Europa is thought to be the most promising location for extraterrestrial life.

9. Titan Moon of Saturn Larger than Mercury
Atmosphere composed of nitrogen with some argon and methane
Has both pure water ice and ice mixed with hydrocarbons.
Hydrocarbons are chemicals that contain the element carbon, which is the building block for all life on Earth.
Titan may also have internal geologic activity which could provide the energy needed for carbon to link up with other elements and make the building blocks of life, such as oils and nucleic acids.

10. End of Ch. 8 Notes