Click here for some advice and guidelines on submitting your answers to study guide questions via email.

Questions from the Part 2 of the lecture notes for Study Guide #3.

(121)

Define what is the meridian. Describe how the length of the Sun's shadow changes during the day, including when it is shortest.

(122)

Describe how the length of the Sun's shadow at local noon changes depending on what day of the year it is. When is the noon shadow shortest and when it is longest? Explain why the shadow changes length depending on the day.

(123)

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.

(124)

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.

(125)

Describe how the Egyptians used decans to keep track of time during the night.

(126)

Explain three reasons why it is easier to use transits to track time rather than rising or setting of the Sun (or a star).

(127)

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

(128)

From the short video on longitude, explain (a) what the prime meridian is and (b) how the experimenter in the video determines the time difference between his location and the Prime Meridian.

(129)

Explain how we use time differences between measurements of local noon in order to determine east/west distance and therefore the longitude of a particular location. Be able to do a very simple calculation like the one described on page 13 of your lecture notes.

(130)

Breifly describe four practical functions of a calendar for the purposes of agriculture, government, commerce or religion.

(131)

Explain how calendars serve a social function that prevents conflict,

(132)

Explain the origin of the alternating numbers of days in our monthly calendar (e.g. March has 31 days, April has 30 days, May has 31 days, June has 30 days, etc.)

(133)

Explain how and why the Egyptians originated the practice of making the year 365.25 days long instead of 365 days.

(134)

Explain the origin of the names of each month in our calendar.

(135)

Explain the origin of the names of each day of our week.

(136)

Explain what are cross-quarter days, and describe two examples of holidays we celebrate that were originally associated with cross-quarter days.

(137)

How are Chinese zodiacal signs determined, and how is this different that the way the Western zodiac works?

(138)

From the Mayan calendar, explain the possible astronomical origin of the 260-day Tzolkin.

(139)

From the Mayan calendar, what is the haab, and how is a Calender Round determined?

(140)

Briefly explain two practical arguments that made it reasonable for ancient philosophers to believe that the Earth does not spin on its axis or orbit around the Sun.

(141)

Although Ptolemy's model of the cosmos fit perfectly with the ancient idea of a stationary Earth, Astronomers over the centuries kept trying to modify or improve on it. Why?

(142)

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

(143)

Although the original Copernican model was much closer to the actual truth of the way planets and the Earth move around the Sun, it was no more accurate about predicting planetary positions than the geocentric models. Explain why.

(144)

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?

(145)

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

(146)

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

(147)

Explain how Galileo's observations of the planet Jupiter helped to cast doubt on the geocentric model.

(148)

Explain how Galileo's observations of the planet Venus helped to cast doubt on the geocentric model. As part of your answer, use a diagram to help explain how his observations of Venus were consistent (in two ways) with the heliocentric model, and explain how they contradicted the geocentric model.

(149)

Describe Tycho Brahe's major contribution to resolving the debate between the geocentric and heliocentric models of the cosmos.

(150)

Describe Johannes Kepler's major contribution to resolving the debate. Kepler's model for the cosmos was similar to that of Copernicus, yet Kepler's model gained wide acceptance very quickly (unlike the Copernican model). What's the main reason for this?

The following five 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.

(151)

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

(152)

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)

(153)

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

(154)

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)

(155)

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)

The following four 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.

(156)

Desribe (a) how Tycho's system differed from the Copernican model, and (b) describe how Tycho's system differed from the standard Ptolemaic geocentric system. (HW)

(157)

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)

(158)

Explain "the problem with star sizes". In other words, (a) why did Astronomers believe that, with the Copernican model, stars would have to be enormously large even compared to our own Sun? And (b) why wasn't this a problem in Tycho's model? Hint: this has to do with parallax. (HW)

(159)

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)

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.

(160)

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)

(161)

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)

(162)

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

(163)

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

(164)

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