Slide 1 Test 1 results Mean: 82 Median: 87

Slide 2 Polar circles 90 o – L – 23.5 o ~ 0, -> L ~ 66.5 o At winter solstice:

Slide 3 The axial tilt angle is not constant, but has a complex motion determined by many cycles of short to very long periods. Due to nutation the tilt oscillates over 9" (about 280 m on the surface) over a period of 18.6 years. The main long-term cycle has a period of years and an amplitude of about 0.68°, or 76 km on the surface. Currently the tilt is decreasing by about 0.47" per year, so the Arctic Circle is moving north by about 15 m per year. Real life complications

Slide 4 Precession

Slide 5 Ecliptic and Zodiac Sun travels 360 o / days ~ 1 o /day Ophiuchus Astrology

Slide 6

Slide 7 History of Astrology Originated by Babylonians about 1000 BC (mundane astrology, i.e. applies to the world) Greeks developed natal (birth) astrology (codified by Ptolemy in Tetrabiblos, 2nd century AD) Argues that a person's character and destiny can be understood from the positions of the Sun, Moon, and planets at the moment of his or her birth.

Slide 8 Astrology — big business 10,000 practicing astrologers 1000 full-time professionals 20 astrological journals 10 new books a week > 1000 newspapers with astrological forecasts 5 million people spend ~ $200 M per year consulting astrologers

Slide 9 Horoscope Natal chart uses astronomical information and date and location of birth Planets, Moon, & Sun in signs of zodiac Interpretation step: positions of celestial bodies are used to predict a person’s character and destiny

Slide 10 Does it work? No evidence that it does Lots of evidence that it doesn’t

Slide 11 Math Corner How do we decide if a test is statistically significant? Coin tossing experiment (flip a coin 20 times and count how many “heads” show up)

Slide 12 Statistically Significant If N hits expected, deviations of sqrt(N) from the expected value Example: flipping a coin 18 flips: 9 plus or minus 3 (33% error) 20,000 flips: 10,000 plus or minus 100 (1% error) If someone claims that he can “predict” the outcome and his predictions are within sqrt(N) of the mean value, he is a liar.

Slide 13 Example (Gauquelin) 15,560 successful individuals in 10 professions –No statistically significant relation between Sun sign and profession Gave a free horoscope evaluation to anyone who wanted it –95% said they recognized themselves –but it was the horoscope of France’s worst mass murderer

Slide 14 Example - Silverman 2978 marriages and 478 divorces in Michigan No correlations between astrological signs and statistics of marriages/divorces found

Slide 15 Example - McGervey Birth dates and biographies of 6000 politicians and scientists Found the astrological signs for both group to be distributed completely at random

Slide 16 Astrology — conclusion No predictive power No scientific basis Broad psychological appeal –Cheap, easy, and entertaining –May help some people (as do many forms of empathetic counseling) –Useless or damaging in other cases

Slide 17 Pseudoscience: Why bother? Many people view science as just another belief system Poor understanding about the difference between science and pseudoscience Widespread ignorance of what constitutes evidence Ideological doctrines (religious, political etc.) obstructed the progress in science and culture many times in history: Inquisition, Nazi Germany, Communist Russia etc.

Slide 18 How to recognize pseudoscience?

Slide 19 Goals Science: The primary goal of science is to achieve a more complete and more unified understanding of the physical world. Pseudosciences are more likely to be driven by ideological, cultural, or commercial goals. Some examples: astrology (from ancient Babylonian culture,) UFO- ology (popular culture and mistrust of government), Creation Science (attempt to justify Biblical interpretation)

Slide 20 Predictive? science: Must be (falsifiability). Workers in the field commonly seek out counterexamples or findings that appear to be inconsistent with accepted theories. pseudoscience: No. A challenge to accepted dogma is often considered a hostile act if not heresy, and leads to bitter disputes or even schisms.

Slide 21 Role of evidence? science: independently verifiable, no contradictions allowed. Each principle must be tested in the crucible of experience and remains subject to being questioned or rejected at any time. pseudoscience: anecdotal, not independently verifiable. Observations or data that are not consistent with established beliefs tend to be ignored or actively suppressed.

Slide 22 Innovation? science: can incorporate new evidence; models change; old ideas are built upon, modified where necessary pseudoscience: relatively rigid and authoritarian since it is not based on empirical evidence. The field has evolved very little since it was first established. The small amount of research and experimentation that is carried out is generally done more to justify the belief than to extend it.

Slide 23 Authority? science: no special “experts” recognized. Scientific ideas and concepts must stand or fall on their own merits, based on existing knowledge and on evidence. pseudoscience: often based on ancient authority; high priests and priestesses

Slide 24 Appeals to our needs and desires? science: may or may not pseudoscience: yes