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28.2 Life in the Solar System

28.2 Life in the Solar System. Life as we know it…. Carbon-based Originated in a liquid water environment. The Moon and Mercury. Lack Liquid water Protective atmospheres Magnetic fields So these bodies receive too much UV radiation, the solar wind, meteoroids and cosmic rays. Venus.

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28.2 Life in the Solar System

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  1. 28.2 Life in the Solar System

  2. Life as we know it… • Carbon-based • Originated in a liquid water environment

  3. The Moon and Mercury • Lack • Liquid water • Protective atmospheres • Magnetic fields • So these bodies receive too much UV radiation, the solar wind, meteoroids and cosmic rays

  4. Venus • Too much atmosphere! • Its atmosphere is too dense, dry, scorching, hot

  5. Jovian Planets • Do not have a solid surface • Some researchers think that life could have evolved in their atmospheres

  6. Pluto and the Jovian moons • Most are too cold • Jupiter’s moon Europa may have liquid water beneath its frozen surface • Saturn’s moon Titan has an atmosphere of methane, ammonia and may have liquid water – but it may be too cold

  7. Europa’s surface

  8. Enceladus – moon of Saturn, with water geysers

  9. Mars

  10. Mars • Probably the planet most likely to harbor life • Water is scarce, but present • The atmosphere is thin • No magnetism or ozone layer • Atmosphere was thicker and planet was warmer in the past

  11. Water on Mars • The Viking and Mars GlobalSurveyor show photographic evidence of flowing and standing water. • In 2004, the European Mars Express confirmed ice (water) at the poles. • Opportunity found evidence that water used to be very abundant.

  12. Evidence of water on Mars

  13. The “Face” on Mars

  14. Life on Mars? • Even with the water and atmosphere and all of the probes that have been to Mars, no life or fossils of life have been found. • Viking robots tested Martian soil for bacteria and other life. • However, the orbiters have not widely surveyed the area. • Particularly, they have not surveyed the area near the polar ice caps.

  15. What do scientists think about Mars today? • Biologists and chemists agree that no life exists on Mars today. • We will need to explore Mars more to learn if life existed there in the past.

  16. Alternative Biochemistry • Would we necessarily recognize life if we saw it? • Could it be different from life as we know it? • Some scientists think that silicon might replace carbon in other lifeforms. • However, its bonds are weaker. • Maybe ammonia is used in place of water.

  17. Alternative Biochemistry • You would have to have lower temperatures for ammonia to remain a liquid. • Colder temperatures are a problem. • There would not be enough energy to drive biological processes.

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