Review for Exam #3
Common theme: potential for life.
Key issues: surface temperature, air pressure, composition of atmosphere
Approach: look to Mars for the "ground truth" about planets near a habitable zone, look to
extrasolar planet detections for the range of possibilities to establish the likelihood of life elsewhere
Topics to weave into the story:
Anthropic principle. Outgassing of atmosphere. Escape of atmosphere. Role of planet mass. Role of temperature,
and the difference between a terrestrial planet and a gas giant. Explanation
of the makeup of the air on Earth vs. other planets like Mars and Venus. Puzzle presented by "hot Jupiters," and
the role of detectability (selection effects). Extrasolar planet detection techniques (Doppler shifts of stellar spectrum, reduction
in brightness due to planet transits). Importance of surface liquid water, and the need for atmospheric pressure to get it.
Evidence for past water on the surface of Mars (rocks that form under water, photos of channels and dried up canyons). Intelligent
life and the Drake equation (highly speculative at this point).
Other topics of relevance to the exam:
The role of rotation on weather, causes of Jupiter stripes, Earth jet streams, Jupiter red spot, Earth hurricanes, the coriolis effect.
The greenhouse effect, temperature of Venus, global warming on Earth.