Ancient Astronomy: The Science of Astronomy - Chapter 3 - Prof. Yanga Fernandez, Exams of Astronomy

Download Ancient Astronomy: The Science of Astronomy - Chapter 3 - Prof. Yanga Fernandez and more Exams Astronomy in PDF only on Docsity! 1 © 2005 Pearson Education Inc., publishing as Addison-Wesley announcements • This week: Ch 3 • Next week: Test #1 on Monday, then Ch 4. • HW #6 is due on Friday -- do the worksheets and then do the MA assignment. • HW #7 is due on Friday October 9 -- it’s a survey. You vote on what topics you want to cover in the second half of the course. • HW #8 will also be due on Friday October 9, at it will be on Chapter 3. © 2005 Pearson Education Inc., publishing as Addison-Wesley announcements • Have you ever seen the ISS? Tonight’s your chance. Between 7:59 and 8:05 it will be visible as a bright moving dot. It’ll appear in the NW, move almost overhead, and then set toward the SE. © 2005 Pearson Education Inc., publishing as Addison-Wesley news • Water on the Moon? Yes, a bit. • Background: Apollo found that Moon rock was completely dry. BUT! They didn’t land near the poles! • What’s new: Three spacecraft have used the reflectance properties of polar Moon rock to infer the existence of water. • How much water? Well not much, about 1 quart of water in 1 ton of rock. And it’s bound tightly to the rock, it’s not in puddles or ice blocks. • But this is a major discovery since it potentially changes the resource game. © 2005 Pearson Education Inc., publishing as Addison-Wesley news © 2005 Pearson Education Inc., publishing as Addison-Wesley Chapter 3 -- The Science of Astronomy This chapter covers some history of astronomy © 2005 Pearson Education Inc., publishing as Addison-Wesley Reading check: 1. Copernicus A. was the first to use a telescope for astronomy. B. hypothesized that ours is a heliocentric Solar System. C. found that planets moved in ellipses around the Sun. D. solidified the notion that the Sun moves around Earth. 2. Galileo A. was the first to use a telescope for astronomy. B. hypothesized that ours is a heliocentric Solar System. C. found that planets moved in ellipses around the Sun. D. solidified the notion that the Sun moves around Earth. 2 © 2005 Pearson Education Inc., publishing as Addison-Wesley Chapter 3 -- The Science of Astronomy • 3.1 : pp. 55-59, but don’t memorize which civilization did what. • 3.2 : pp. 59-62, “geocentric” Universe. • 3.3 : pp. 62-68, Copernican revolution. • 3.4 : pp. 68-73, “what is science” Much of this chapter is narrative - don’t get bogged down in memorizing all the historical facts. Remember the important ones. © 2005 Pearson Education Inc., publishing as Addison-Wesley 3.1 The Ancient Roots of Science • WHY --- Why did ancient societies care about astronomical phenomena? • WHAT --- What did ancient civilizations achieve in astronomy? (And what couldn’t they know before the invention of the telescope?) The main point here is that: © 2005 Pearson Education Inc., publishing as Addison-Wesley Why did ancient societies care about astronomical phenomena? • They kept track of time, seasons, planetary motion: – for practical purposes, including agriculture – for religious and cultural purposes • They had to know the sky for navigation © 2005 Pearson Education Inc., publishing as Addison-Wesley What did ancient civilizations achieve in astronomy? • daily timekeeping • tracking the seasons and calendar • monitoring lunar cycles • monitoring planetary cycles • change of constellations through the year • predicting eclipses • and more… HOW DID THEY FIGURE THIS ALL OUT? © 2005 Pearson Education Inc., publishing as Addison-Wesley HOW DID THEY FIGURE THIS ALL OUT? PATIENT OBSERVATION! This is an important point: Given enough time and a sufficiently clear sky, you can learn a great deal about the Solar System without any technology whatsoever. © 2005 Pearson Education Inc., publishing as Addison-Wesley What couldn’t ancient civlizations have known? A. Time it takes for the Moon to go through all its phases. B. Time it takes for one of Jupiter’s moons to go once around that planet. C. Time it takes for the Sun to travel all the way through the zodiac. D. The day that the Sun will reach its highest point in the sky at noon. 5 © 2005 Pearson Education Inc., publishing as Addison-Wesley That said -- there were Greeks that thought the heliocentric model was better: -- Heraclides (4th C., BC) -- Aristarchus of Samos (3rd C., BC) It is important to note that every piece of observational evidence for a heliocentric Solar System could have existed in ancient Greece. It didn’t require advanced technology or higher math, just careful measurement and experimentation. We did not have to wait for Copernicus and that gang ~2000 years later. © 2005 Pearson Education Inc., publishing as Addison-Wesley 3.3 The Copernican Revolution What are Kepler’s three laws of planetary motion? This section has more narrative about the development of the heliocentric model. What we’ll cover in detail in class is: © 2005 Pearson Education Inc., publishing as Addison-Wesley Summary of the Big 4: • Nicholas Copernicus: created a heliocentric model of the Solar System that still used circular orbits. ALSO -- it had just as many epicycles as the Ptolemaic model! The model was good at explaining retrograde motion, but turns out not so good for predicting positions of planets. He does not overthrow the Ptolemaic model. • Tycho Brahe: was the best observer of his (pre-telescopic) day. Made (relatively) high accuracy observations of the planets with which he wanted to definitively confirm whether we lived in a geocentric, heliocentric, or a hybrid Solar System. Died before he could do it. But at least he got the data! © 2005 Pearson Education Inc., publishing as Addison-Wesley • Johannes Kepler: analyzed Brahe’s data to solve the problem. He found that a heliocentric Solar System with elliptical (not circular) orbits did the best job of explaining where the planets were in the sky. • Galileo: performed experiments and observations that put the nails in the coffin for the geocentric model. More later…. Summary of the Big 4: © 2005 Pearson Education Inc., publishing as Addison-Wesley • Nicholas Copernicus • Tycho Brahe • Johannes Kepler • Galileo Galilei Know the Big 4: © 2005 Pearson Education Inc., publishing as Addison-Wesley …that he found by trial-and-error. But only three of them turned out to be right. So we have Kepler’s Three Laws of Planetary Motion Kepler had lots of “laws”.… 6 © 2005 Pearson Education Inc., publishing as Addison-Wesley Kepler’s First Law: The orbit of each planet around the Sun is an ellipse with the Sun at one focus. Kepler’s three laws of planetary motion. © 2005 Pearson Education Inc., publishing as Addison-Wesley All objects in the Solar System travel on ellipses. Sometimes the ellipses are elongated (e.g. for comets), sometimes they are nearly circular (e.g. for planets). © 2005 Pearson Education Inc., publishing as Addison-Wesley Which ellipse and orbit most closely resembles Earth’s true situation? A. B. D.C.