Study Guide for 1ST Astronomy Exam

Study Guide for 2ND Astronomy Exam

The successful student will be able to… Unit 8: The Lunar Cycles  Describe the daily and monthly apparent motion of the Moon and its relationship to the Zodiac. o Study Hint: Summarize the diurnal and monthly motion of the Moon on a 3x5 card and include the lunar synodic period and the significance of the zodiac.  Draw and interpret Figure 8.1 illustrating the lunar phases and the Moon’s relationship to the Sun at each principle phase. o Study Hint: Draw a picture of the full moon, identify where it is in its orbit as in Figure 8.2 and state the configuration the Moon is in with respect to the Sun. Do the same for the New Moon, 1st Quarter Moon and 3rd Quarter Moon  Name the phase of the Moon from a photograph of the Moon. o Study Hint: Make eight simple drawings of the “Appearance of the Moon from Earth” as in Figure 8.2 on eight different 3x5 cards. Write the name of the phase on the back. Quiz yourself.  Estimate the number of days between lunar phases. o Study Hint: Remember the lunar syndic period is 29 ½ days which is pretty close to four weeks. Thus the time between principle lunar phases (New, 1st Quarter, Full, 3rd Quarter) is approximately 1 week.  Rank images of the Moon in different phases in order of occurrence first to last. o Study Hint: Go to the Interactives link of University of Nebraska, Lincoln and check the On-line Ranking and Sorting Tasks titled Phase Order (http://astro.unl.edu/interactives/lunar/PhaseOrder.html ). Practice putting the phases in order.  Characterize the Moon’s apparent motion given its phase and the time of year. o Study Hint: Recall that on a daily basis the Moon appears to move westward with the stars as if attached to the celestial sphere (almost anyway). Thus the Moon will share the apparent motion properties of the stars around it. If the Moon is north of the Celestial Equator it will share the properties of northern stars. If the Moon is south of the Celestial Equator it will share the properties of southern stars. If the Moon on the Celestial Equator it will share the properties of stars on the Celestial Equator. If you can characterize the apparent motion of these three types of stars they you can characterize the apparent motion of the Moon.  Explain why the lunar sidereal period is different than the time for a cycle of lunar phases. o Study Hint: On a 3x5 card write out the question above and on the back write your answer following the description in the text in Figure 8.4 and Unit 8.1 Unit 10: Geometry of the Earth Sun and Moon  Use the angular size relation to estimate the distance or true size of an astronomical object form a photograph. o Study Hint: Review the angular size problems posted on Hot Tips (in the HW solutions and in Week 04. Do the extra credit on the diameter of Jupiter. Unit 11: Planets the Wandering Stars  Describe the characteristics of the inferior and superior planets as regards their apparent motion in the sky. (Motion, elongation, configuration while retrograde…) o Study Hint: Review the table of apparent planetary motion found in Hot Tips under Week 05 Day 10 Lecture Notes. Make 3x5 cards for each planet summarizing their motion.  Work with and identify planetary configurations of opposition, conjunction, quadrature and maximum elongation. o Study Hint: Practice with the Planetary Configuration Simulator on Hot Tips Week 05  Describe the basic ideas of the Copernican model of the Universe. o Location and Motion of the Earth o Location of the planets and the observational basis for that ordering. (See Figure 11.10)  Describe the cause of retrograde motion in our modern Copernican Model. o Study Hint: On a 3x5 card write the question out above and then your answer on the back (Unit 11.3). Review it.  Describe why inferior planets demonstrate a maximum elongation in their motion. o Study Hint: On a 3x5 card write the question out above and then your answer on the back (Unit 11.3). Review it.  Describe how Copernicus determined the relative distances of the planets from the Sun. o Study Hint: On a 3x5 card write the question out above and then your answer on the back (Figure 11.10). Review it. Unit 12: The beginnings of modern astronomy  Discuss Galileo’s observations of the Sun. Moon, Jupiter and Venus and state how they contradicted the previously held Aristotelian model of the Universe. o Study Hint: On a 3x5 card describe what Galileo saw when he observed the Moon and state how it contradicted the previously held Aristotelian model. o Study Hint: On a 3x5 card describe what Galileo saw when he observed the Sun and state how it contradicted the previously held Aristotelian model. o Study Hint: On a 3x5 card describe what Galileo saw when he observed Jupiter and state how it contradicted the previously held Aristotelian model. o Study Hint: On a 3x5 card describe what Galileo saw when he observed Venus and state how it contradicted the previously held Aristotelian model.  Describe Kepler’s three laws of planetary motion and state how the first two laws were contrary to the previously held ideas of Aristotle and Ptolemy. o Study Hint: On a 3x5 card state Kepler’s 1st Law, draw a picture of an ellipse, identify the foci and the location of the Sun in the ellipse, identify aphelion and perihelion on the ellipse, define the eccentricity. o Study Hint: On a 3x5 card state Kepler’s 2nd Law, draw a picture of an ellipse and indicate aphelion and perihelion and where the planet is fastest and slowest on its orbit. o Study Hint: On a 3x5 card state Kepler’s 3rd Law and give an example of it applied to a planet in our solar system. Unit 16: The Universal Law of Gravitation  Describe the characteristics of gravity in words and in an equation. (16.2) o Study Hint: On a 3x5 card state write a list of bulleted points that describe the force of gravity and write the universal law of gravitation. Review it often.  Describe and illustrate by example the nature of the inverse square law as it applies to gravity. o Study Hint: On a 3x5 card describe the inverse square law and write a numerical example of the effect of the inverse square law. Review it often.  State the significance of the low value for G. o Study Hint: On a 3x5 card state the significance of the low value for G. Review it often. Unit 17: Measuring a Body’s Mass using Orbital Motion  Describe what an astronomer needs to observe to calculate the mass of a distance body using properties of the distant body’s satellite. o Study Hint: On a 3x5 card sketch the right-hand side of Figure 34.6 and summarize the caption of that figure. Review it often. Unit 18: Orbital and Escape Velocities  Describe how the orbital velocity of an object in circular orbit depends on the distance from the central object and how the orbital velocity depends on the mass of the central body. o Study Hint: On a 3x5 card define orbital velocity, write the equation, and state how the orbital velocity depends on distance and the mass of the central object. Review it often.  Describe how the mass of an orbiting object affects its orbital velocity. o Study Hint: On a 3x5 card state the effect of the orbiting objects mass on its orbital velocity. Unit 34: The Structure of the Solar System  Write an essay contrasting the properties of the Terrestrial and Jovian Planets o Study Hint: On two 3x5 cards make a bulleted list of the properties of the Terrestrial and Jovian Planets.  Calculate the density of a planet given its radius and mass o Study Hint: On a 3x5 card write a planets radius in km and mass in kg and then do a sample calculation of a planet’s density in g/cm3.  List or identify the following characteristic of any planet in our solar system o Distance from the Sun in AU . Study Hint: on a 3x5 card write the distances of the planets from the Sun in AU and sketch a meter stick (39 inches) and label where the planets would appear on that meter stick if 1AU = 1 inch. o Mass in Earth masses . Study Hint: on a 3x5 card write the masses of the planets from in Earth mass units . Make an anology to monetary units (e.g. Earth mass = $1.00, then Mercury is a nickle, Mars is a dime, and Venus is 80 cents, etc…) o Radius in Earth radii . Study Hint: on a 3x5 card write the radii of the planets in Earth radii. Note that the terrestrial planets follow the pattern of 1, ½, 1/3, ¼ where Venus is about 1 Earth radius, Mars is ½ an Earth radius, Mercury is 1/3 of an Earth radius, and the Moon is ¼ of an Earth radius. 3 o Density in g/cm . Study Hint: on a 3x5 card write the densities of the planets in g/cm3. Note that the densities of the Terrestrial planets are all about 5.5 g/cm3 except Mars which is 3.9 g/cm3 and the densities of the Jovian planets are all about 1.2 g/cm3 except Saturn that is 0.7 g/cm3. . Study Hint: Note that Saturn in the “95” planet since it is 9.5 AU from the Sun, has a mass of 95 Earth masses and has a radius of 9.5 Earth radii. Now how hard is that to remember! . Study Hint: On separate 3x5 card write the properties of Jupiter – this planet will be especially important coming up.

Plus… o Use ratios to compare sizes of astronomical objects. o Use a proportion to calculate a scale model of an astronomical object. o Estimate the angular size of an object from a photograph with a known field of view. o Use the angular size relation to calculate an objects true size or distance.