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Questions from the third part of the class, to be covered on Exam #3.

(97)

What is the definition of "the meridian"? What do we mean when we say an object "transits"?

(98)

Describe how gnomons keep time on a sunny day. When is the shadow cast by a gnomon the shortest, and how does the length of the shortest shadow vary over the course of a year (think about how the maximum altitude of the Sun changes during the year on our horizon diagrams)?

(99)

Explain why it is easier to time an object's meridian crossing ("transit") as opposed to the object's rising or setting times (three reasons).

(100)

What is the analemma? Use a horizon diagram to help explain what causes the north-south motion of the Sun along the meridian over the course of a year.

(101)

Explain what causes the East-West motion of the Sun in the analemma during the year. Use a diagram to help explain why the solar day (time between sun meridian crossings) is sometimes a little longer and sometimes a little shorter than 24 hours.

(102)

Explain how you can determine the latitude of your observing location at night. Describe what you must observe to determine latitude during the day.

(103)

Two of the most easily recognizable constellations that are up in the sky at this time of year are Ursa Minor and Gemini. Find the following information about these two constellations:

• Approximate location in the evening sky this month, based on the star chart in your book for Apr/May/Jun,
• star chart (sketch of the pattern of the 6-8 brightest stars and connecting lines that make up the constellation),
• name of the two stars designated alpha and beta (usually the two brightest),
• 2-3 sentence summary of the mythology behind the constellation.

This is pretty easy to find on the web. A good place to go for mythology is http://www.emufarm.org/~cmbell/myth/myth.html, but remember to keep your summary fairly short so it is easy to remember the most important parts. A good place to go for simple star charts is http://www.dibonsmith.com/constel.htm. For star names and other information, try http://www.astro.wisc.edu/~dolan/constellations/. To find the approximate altitude and azimuth (azimuth means direction along the horizon, like northeast, south, west, etc), you should use the star chart as indicated, but you may also consult the Starry Night software that comes with your book (this is also installed on the computers in the Astronomy lab, which you can use if you finish early in lab) ***OR*** go outside and *FIND* them with your own two eyes on a clear night (all are easily visible this time of year). When you are done, go out at night and find the constellation and explain what you know to a friend or classmate. It's fun to do and easier to remember that way. (HW)

The following six questions come from the the November 1992 Scientific American article "Astronomy in the Age of Columbus". This is not available in the digitized TCU library archives. Instead, you can find it under "Content" in the 10293 page on d2l.tcu.edu.

(104)

Describe two arguments used by Aristotle that indicated the ancient Greeks understood that the Earth must be spherical and not flat. (HW)

(105)

Why was it popularly believed among early American settlers that most European authorities believed that the Earth was flat during the time of Columbus? (HW)

(106)

Describe the two "errors" Columbus made about Earth's geography that made his proposed Westward voyage to Asia seem more reasonable and possible (HW)

(107)

Explain how Columbus used the reference book "Ephemerides" (which provided timing of astronomical phenomena such as lunar phases and eclipses) to help during his voyage.(HW)

(108)

Describe two historical changes that occurred around the time of the publication of Copernicus' heliocentric theory that helped ensure it got a serious hearing in the scientific community, unlike times in the past when it had been suggested by others. (HW)

(109)

Name and explain three different arguments or lines of evidence (different from historical changes discussed in the previous question) that helped prompt the revolutionary change in consensus from Ptolemy's geocentric model (described in "The Almagest") to a Copernican heliocentric model. (HW)

The following three questions come from the January 2014 Scientific American article "The Case Against Copernicus". While this article is available in the online TCU Library archives, you can also find it under "Content" in the 10293 page on d2l.tcu.edu.

(110)

Describe how Tycho's system differed from the standard Ptolemaic geocentric system, and explain why Tycho felt it was unreasonable that the Earth move quickly about the Sun but perfectly reasonable for the other planets to move quickly in their orbits around the Sun or Earth. (HW)

(111)

Galileo's famous observations of the moons of Jupiter and the phases of Venus contradicted the standard geocentric model but were fully consistent with Tycho's model. For each observation, explain how and why. (HW)

(112)

The Italian astronomer Riccioli argued that the Earth cannot be rotating on its axis and orbiting the Sun because of two scientific arguments that would not be refuted until centuries later. Describe each argument briefly and explain how each was eventually refuted. (HW)

(113)

How many miles per hour, approximately, does the Earth move? About how long (how many seconds) does it take for the Earth's surface to rotate through a distance of one mile? Use this fact to explain why navigational maps required extremely precise clocks.

(114)

Suppose you are West of Fort Worth and you know the Sun transits (crosses the meridian) at noon in Fort Worth. In your location, you notice that the Sun crosses the merdian 30 minutes after noon, so roughly how far west of Fort Worth are you in miles?

The following five homework questions are from Chapter 11 of the book "Echoes of the Ancient Skies," which can be found in the Doc Sharing section of the Physics 10293 course on e-College.

(115)

What is the origin of the term "feng-shui", a technique used today even in America to design homes and neighborhoods? (HW)

(116)

Templo Mayor in the ancient Aztec city of Tenochtitlan is skewed from a cardinal alignment so that it faces 7 degrees south of east instead of due east like most other buildings. Nevertheless, the Aztecs used the building to mark the days of the equinox, when the Sun rose directly East. Explain how the Aztecs used this "misaligned" building to mark the sun's location on the equinox (use a diagram to help with this answer). (HW)

(117)

Explain what a ceque and a huaca is to the Inca. How did the Inca use these to organize their empire? (HW)

(118)

Near Cuzco, at a place known as Mismanay, the city is divided into four parts, with the intersection at a chapel known as Crucero. Explain how the motion of the Milky Way in the sky (unique to this specific latitude) inspires these paths which point along the intercardinal (NE, NW, SE, SW) directions. (HW)

(119)

The Pyramid of the Sun in the Aztec city of Teotihuacan seems to face in a direction perpendicular to the main avenue, the "street of the dead" through the city. This direction is also the same as the alignment marked by the Viking Group pecked cross and the Cerro Colorado pecked cross (seen in the photo on page 282). First, what is a pecked cross? Second, what do we think the Pyramid of the Sun was actually pointed toward, astronomically, and why would that astronomical object be significant? (HW)

(120)

Explain how the location of Earth's Moon in the sky can be used to tell time. Why was it difficult to use?

(121)

Explain how Galileo's observations of Jupiter gave him the ability to determine the time. How was this method implemented in practice?

The following five homework questions are from Chapter 12 of the book "Echoes of the Ancient Skies," which can be found in the Doc Sharing section of the Physics 10293 course on e-College.

(122)

What did the crossed sticks symbolize to Mesoamerican? What evidence supports this interpretation of the crossed sticks? (HW)

(123)

What was patolli, and how is its design related to the designs seen in the Codices (such as Fejervary-Meyer and Madrid)? (HW)

(124)

Describe the cosmology of the Aztec. Specifically, what were their "ages" and how did they end? How will our current age end, according to the Aztec, and how do we know this from carvings like the Aztec calendar stone? (HW)

(125)

Explain the evidence that indicates that the early Babylonians were careful observers of Venus and aware of its cyclical motion through the sky. What is the possible reason given in the text that Venus was represented in drawings and on stones as an eight-pointed star? (HW)

(126)

What does the winged disk symbolize in Egyptian architecture? What evidence tells us that the Egyptians used measurements along the horizon to keep track of the dates? (HW)

(127)

Name and explain two of the major cultural purposes that a calendar serves for a large kingdom/empire in the ancient world.

The following five questions come from the the April 1986 Scientific American article "Islamic Astronomy". This is not available in the digitized TCU library archives. Instead, you can find it under "Content" in the 10293 page on d2l.tcu.edu.

(128)

Name and explain two arguments put forth by the author to explain why the study of Astronomy because a prominent part of Islamic culture during the Dark Ages (8th-14th century). (HW)

(129)

Name and briefly explain two complications that arose from attempts to use a lunar calendar in order to track seasonal changes (one has to do with the Metonic cycle, the other with the timing of the beginning of the month). (HW)

(130)

Briefly describe two religious customs in Islam that require the application of precise observational Astronomy. (HW)

(131)

Explain how astrolabes contributed to the fact that most prominent navigational stars today have Arabic names. (HW)

(132)

Explain why Islamic astronomers did not really take note of or try to explain one-time occurrences in the sky like supernova explosions. (HW)

Visit https://maya.nmai.si.edu/calendar/calendar-system to learn about the Mayan calendar, and answer questions 139-141.

(133)

Describe the Haab calendar cycle. How many days does it have, and how are those days divided? (HW)

(134)

Describe the Tzolk'in calendar cycle. How many days does it have, and how are those days divided? What are three other 260-day cycles or periods of time that may also be linked to the origin of the Tzolk'in? (HW)

(135)

Describe the Calendar Round. How is it created, and how long does it last? (HW)

(136)

What are the origins of the names of the months March, April, May and June?

(137)

Explain where the names of the months September, October, November and December originate.

(138)

Explain the names of the months July, August, January and February.

(139)

Explain how the date of Easter is determined each year.

(140)

What are cross quarter days and where do they fall on the calendar during our year? Give two examples of cross-quarter holidays we observe in America.

(141)

Briefly explain the history ofthe Gaelic holiday (Cailleach) that was eventually turned into our Groundhog Day.

(142)

Explain the 12-year Chinese calendar cycle and how their "zodiac" compares to ours. On what celestial body is this cycle based?

(143)

Explain why predicting planetary motions is complicated. Describe what a retrograde loop is and how it impedes successful long-term predictions of planetary motion.

The following six study guide questions are from the online resource by Ian Ridpath known as "Star Tales," which many of you have used as a source for stories about the constellations. Please read through the introductory chapters one and two (found at http://www.ianridpath.com/startales/contents.htm) to answer the following:

(144)

(From chapter 1, page 1a) The constellations we use today were first published as a set by Ptolemy in his book known as the Almagest. Explain the two lines of evidence (one of them written, one of them having to do with the gaps in the star maps) that many of the constellations in Ptolemy's book likely originated from the Babylonian civilization that existed about 800 years prior to Ptolemy's era. (HW)

(145)

(From chapter 1, page 1b) Describe the evidence for and against the hypothesis that the Minoan civilization centered on the island of Crete was the primary source of constellations recognized by the Greeks and Ptolemy. (HW)

(146)

(From chapter 1, page 1c) Explain the origin of two large constellations in the Northern celestial hemisphere: Camelopardalis and Monoceros. What was the role of Petrus Plancius in filling in the Southern Celestial hemisphere with 12 new constellations, previously uncharted? (HW)

(147)

(From chapter 1, page 1d) Explain the role of Johannes Hevelius in the modern set of recognized constellations. Explain the role of Lacaille in the modern set of constellations. Why are there so many constellations named after scientific instruments (e.g. Telescopium, Microscopium) in the Southern celestial hemisphere? (HW)

(148)

(From chapter 2, page 2a) What is the Farnese Atlas? Explain its historical significance. What is the Dunhuang star chart? Explain its historical significance. (HW)

(149)

(From the page on Chinese constellations, linked from page 2a) Explain how the Chinese constellations originally organized the sky. In particular, describe lunar mansions and the four-part zodiac. Also, explain two reasons why it is very difficult to determine the identifications of specific stars within constellations from Chinese star charts. (HW)

(150)

Describe briefly how each of the two main theories of planetary motion (geocentric and heliocentric) explain the pheonmenon of retrograde motion.

(151)

Describe the parallax method for determining stellar distances with the help of a simple diagram. What do we measure when we measure "parallax" and what do we deduce from these measurements?

(152)

Explain why in the heliocentric system, we expect stars to show evidence of parallax angles. How do supporters of a heliocentric model explain away the lack of observed parallax?

(153)

How do supporters of the geocentric model explain the lack of observed parallax angles?

(154)

Use the equation of angular size to explain why, in the heliocentric system, the actual sizes of stars were apparently enormously larger than the Sun, based on what we observed from Earth, which was an argument against the heliocentric theory.

(155)

Use diagrams to help explain how Galileo's observations of the planet Venus helped support the heliocentric model.

(156)

Explain the contribution made by Kepler that finally encouraged scientists to accept the heliocentric model. How was Kepler able to check his model before publication and make sure his predictions would be so accurate?

(157)

Explain what Newton's law of universal gravitation is, how it explains planetary orbits ("Why does the apple fall but the Moon remains in the sky?").

(158)

How is Newton's view of gravity different from previous ideas about the way the universe works? Explain how it helped satisfy some of the earliest criticisms of the heliocentric model.