Part III: Impacts, the Sun, Solar System History, and Life in the Universe

Astrology and Pseudoscience

• Fundamental ideas of astrology.
• Requirement for new unknown force.
• Testing astrology in a fair and rigorous way.
  • Results of in-class experimet with sun-sign astrology.
  • Results of more stringent experiments.
• Themes of pseudoscience; examples and how to tell pseudoscience from objective science.

Impacts!

• impact record of the Moon compared with the inner planets
• terrestrial impacts.
• the impact hazard scale: small impacts are more frequent
• crater size related to impactor size (crater 10x larger than impactor).
• effects of large impacts on life on Earth
• extinction of the dinosaurs: evidence of an impact causing it
• other sample impacts: Arizona meteor crater, Tunguska, Comet SL9 and Jupiter.

The Sun

• Observed parameters of the Sun: temperature, size, luminosity.
• The solar photosphere, chromosphere and corona.
• Granulation, sunspots, prominences, flares.
• Sunspots, magnetic fields and the 22 year sunspot cycle.
• Energy generation in the Sun via nuclear fusion.

Formation of the solar system

• Collapse of the sun and solar system out of a molecular cloud.
  • Gravitational collapse
  • formation of a disk.
• Formation of planets in the solar nebula via
  • condensation
  • planetessimal formation
  • accretion
• Temperature distribution in the solar nebula
• The'frost line' and formation of icy vs. rocky planets
• Time scale for planet formation was short (<<100 million years) compared with the age of the solar system.

Other Solar Systems

• Observational challenge of finding planets around other stars
• Planet detection methods based on 'wobbling' of stars under gravitational influence of surrounding planets.
• The radial velocity technique as the most prolific.
• Discoveries over the past 15 years of > 320 planetary systems
• the 'Hot Jupiter' issue
• Questions arising from these discoveries (i.e. is our solar system typical?)
• Searching for other Earth-like planets

Life in the Universe

• The probability of life on other planets - assumptions and guesses.
  • Drake's estimator of the probability of finding a technological civilization in the galaxy.
  • Astronomical, biological, and sociologicaly factors.
• The habitable zone - liquid water and the development of life.
• Likely values for each factor in the Drake Equation.
• Which terms in the Drake "equation" are more certain, which are not.
• The Search for Extra-Terrestrial Intellegence (SETI).
  • Methods used by SETI in the search for artificial signals from space.
  • Why radio waves are a good way of transmitting signals across the Galaxy?
  • Current searches and results.
  • Future prospects