Chapter 3 The Science of Astronomy Copyright 2009 Pearson Education Inc The NASA budget declining Copyright 2009 Pearson Education Inc Copyright 2009 Pearson Education Inc We have more astronomy satellites now than we have ever had A golden age of astronomy at NASA Copyright 2009 Pearson Education Inc What is science Some questions Question Do you believe there is evidence of Global Warming A Yes B No C Not sure Copyright 2009 Pearson Education Inc Next question Do you believe that the evidence shows that human activity is causing Global Warming A Yes B No C Not sure Copyright 2009 Pearson Education Inc The same question Question do you believe there is evidence of Global Warming A Yes B No C Not sure Copyright 2009 Pearson Education Inc Science Science requires data taking The data must be held to very high standards and must be repeatable Science also requires hypotheses to test against the data A hypothesis that gives no prediction is pretty much useless Karl Popper the idea of falsifiable A hypothesis that has been checked over and over again and found to be true is a theory Copyright 2009 Pearson Education Inc 3 1 The Ancient Roots of Science Our goals for learning In what ways do all humans employ scientific thinking How did astronomical observations benefit ancient societies What did ancient civilizations achieve in astronomy Copyright 2009 Pearson Education Inc In what ways do all humans employ scientific thinking Scientific thinking is based on everyday ideas of observation and trial and error experiments Copyright 2009 Pearson Education Inc How did astronomical observations benefit ancient societies In keeping track of time and seasons for practical purposes including agriculture for religious and ceremonial purposes In aiding navigation but they also created a corrupt class based on pseudo scientific rites Knowledge not shared can corrupt Copyright 2009 Pearson Education Inc What did ancient civilizations achieve in astronomy Daily timekeeping Tracking the seasons and calendar Monitoring lunar cycles Monitoring planets and stars Predicting eclipses Great parties on New Years Eve Human sacrifice And more Copyright 2009 Pearson Education Inc Egyptian obelisk Shadows tell time of day Copyright 2009 Pearson Education Inc England Stonehenge completed around 1550 B C Copyright 2009 Pearson Education Inc Mexico Model of the Templo Mayor Copyright 2009 Pearson Education Inc New Mexico Anasazi kiva aligned north south Copyright 2009 Pearson Education Inc SW United States Sun Dagger marks summer solstice Copyright 2009 Pearson Education Inc Scotland 4000 year old stone circle Moon rises as shown here every 18 6 years Copyright 2009 Pearson Education Inc Peru Lines and patterns some aligned with stars Copyright 2009 Pearson Education Inc Macchu Pichu Peru Structures aligned with solstices Copyright 2009 Pearson Education Inc South Pacific Polynesians were very skilled in the art of celestial navigation Copyright 2009 Pearson Education Inc I think this is crap France Cave paintings from 18 000 B C may suggest knowledge of lunar phases 29 dots Copyright 2009 Pearson Education Inc On the Jisi day the 7th day of the month a big new star appeared in the company of the Ho star On the Xinwei day the new star dwindled Bone or tortoiseshell inscription from the 14th century B C China Earliest known records of supernova explosions 1400 B C Copyright 2009 Pearson Education Inc What have we learned In what ways do all humans employ scientific thinking Scientific thinking involves the same type of trial and error thinking that we use in our everyday lives but in a carefully organized way How did astronomical observations benefit ancient societies Keeping track of time and seasons navigation Copyright 2009 Pearson Education Inc What have we learned What did ancient civilizations achieve in astronomy To tell the time of day and year to track cycles of the Moon to observe planets and stars Many ancient structures aided in astronomical observations Copyright 2009 Pearson Education Inc 3 2 Ancient Greek Science Our goals for learning Why does modern science trace its roots to the Greeks How did the Greeks explain planetary motion How did Islamic scientists preserve and extend Greek science Copyright 2009 Pearson Education Inc Our mathematical and scientific heritage originated with the civilizations of the Middle East following roughly the dispora of the family of Abrahm Copyright 2009 Pearson Education Inc Artist s reconstruction of the Library of Alexandria Copyright 2009 Pearson Education Inc Why does modern science trace its roots to the Greeks Greeks were the first people known to make models of nature They tried to explain patterns in nature without resorting to myth or the supernatural Greek geocentric model c 400 B C Copyright 2009 Pearson Education Inc Greek Science was not like ours The Greeks were very careful about the difference between truth and theory They did not necessarily believe that the planets did what was said in their theory The theory was just a model Truth was unknowable it was faith Copyright 2009 Pearson Education Inc Special Topic Eratosthenes measures the Earth c 240 B C Measurements Syene to Alexandria distance 5000 stadia angle 7 Calculate circumference of Earth 7 360 circum Earth 5000 stadia circum Earth 5000 360 7 stadia 250 000 stadia Compare to modern value 40 100 km Greek stadium 1 6 km 250 000 stadia 42 000 km Copyright 2009 Pearson Education Inc How did the Greeks explain planetary motion Underpinnings of the Greek geocentric model Earth at the center of the universe Heavens must be perfect objects move on perfect spheres or in perfect circles Plato Aristotle Copyright 2009 Pearson Education Inc But this made it difficult to explain the apparent retrograde motion of planets Review Over a period of 10 weeks Mars appears to stop back up then go forward again Copyright 2009 Pearson Education Inc The most sophisticated geocentric model was that of Ptolemy A D 100 170 the Ptolemaic model Sufficiently accurate to remain in use for 1500 years Arabic translation of Ptolemy s work named Almagest the greatest compilation Ptolemy Copyright 2009 Pearson Education Inc So how does the Ptolemaic model explain retrograde motion Planets really do go backward in this model Copyright 2009 Pearson Education Inc Thought Question Which of the following is NOT a fundamental difference between the geocentric and Sun centered models of the solar system A B C D Earth is stationary
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