WEEK 5 LECTURE NOTES
WEEK 5 LECTURE NOTES ASTR 121
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This 5 page Class Notes was uploaded by Anisa sudra on Saturday May 2, 2015. The Class Notes belongs to ASTR 121 at University of Oregon taught by Scott Fisher in Spring 2015. Since its upload, it has received 79 views. For similar materials see ASTR 121 The Solar System in Astronomy at University of Oregon.
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Date Created: 05/02/15
5215 355 PM Photo of the day Moon la luna moon flower 0 Infrared and ultraviolet picture of encleadus observed by cassini o The ultraviolet is what highlights the texture and ridges 0 photo of encelaudus to scale in reality everything is various sizes They just show similar sizes in photos 0 Major Moons around the system of Sol within the solar system 0 Finding life best case europa and enceladus Moon phases 0 28 days for the moon to go around the earth 1 month if you keep constant track of the moon you see more and more of the moon as the month progresses Moon goes thru a cycle once a month in which we can predict for years Why do we see phases of the moon I Lunar phases are a consequence of the moon s 273 day orbit around earth a As the moon orbits we can see more and more of the side that is lit by the sun a Moon 15quot away from earth on grapefruit scalequot a From earth to the moon 25 million miles 0 Sun is 400x further away than the moon Why do we see phases of the moon a Half of the moon is illuminated by the sun reflected sunlight and half is dark It makes no light itself a We see a changing combo of the bright and dark faces as the moon orbits earth a New moon up during the day and we can see it bc the sun is so bright it makes the sky brighter and bc we are looking at the side of the moon that is not illuminated a Full moon when we can see the illuminated side a Quarter moon quarter of the moon is illuminated etc o Phases are just different parts of the moon we can see that are being illuminated we only see one side of the moon a synchronous rotation o the moon rotates exactly once with each revolution around the earth 0 This is why only one side is visible form earth 0 The earth and the moon are tidally locked the back side of the moon photo which was taken behind the moon as the spacecraft flew around it this shows the side of the moon that never faces the earth due to synchronous rotation n this dark sidequot isn t darkjust the other side 22 the reason for seasons 0 the real reason for seasons is the tilt of the earth s axis 0 The altitude of the sun changes with seasons 0 Sun s position a noon in the summer higher altitude means more direct sunlight o The shape of the path of the sun analemma o Sun s position at noon in the winter lower altitude means less direct sunlight look at image in book for graphic Seasons depend on how earth s axis affects the directness of sunlight o How does the orientation of earth s axis change with time o The axis precesses over about 26000 years Which means Polaris wont always be the north star 0 PRECESSION o The 2 systems of constellations are no longer aligned 0 Reason why astrology does not work 0 The stars move over time therefore the stars when you were born are not in the same place they are now WEDNESDAY 42915 Video driving on the moon Reading assignment 0 Read ch 3 esp 34 o Read ch 5 esp 53 0 Extra credit Hw 4 o Astro blog 34 the Nature of Science 0 goals 0 how can we distinguish science from nonscience Or more importantly a psedoscience o What is a scientific theory Science vs non science 0 The word comes from the atin scientia meaning knowledge 0 Not all knowledge comes from science The idealized scientific method 0 Based on proposing and testing hypotheses o Hypothesis educated guess FRIDAY 5115 Hallmarks of science Modern science seeks explanation for observed phenomena that rely solely on natural causes A scientific model must made testable predictions about natural phenomena that would force us to revise of abandon the model if these predictions do not agree You must start over THEORY has different meaning in science than in everyday life 0 in science a theory is no the same as a hypothesis A scientific theory must 0 Explain a wide variety of observations with a few simple principles 0 Be supported by a large compelling body of EVIDENCE NOT have failed any crucial test of its validity HCW distinguish science from non science Chapter 53 TELESCOPES Extra credit observatory extra credit kiosk in eug due may 15 5215 355 PM