Physics 014 The Astronomer s Universe Fall Midterm 1998 Instructor Brad Waugh Date October 19 1998 All answers should be written on the answer sheet provided You may keep the rest of the exam Short Answer Questions 5 questions worth 4 marks each 20 marks Q1 Briefly give four of Aristotle s arguments for the Earth having a spherical shape Q2 In brief write down Kepler s three laws of planetary motion What is the constant from the third law for the solar system in the following units astronomical units years and solar masses Q3 In brief write down Newton s three laws of motion Circle the one that is equivalent to Galileo s law of inertia Q4 Briefly give three elements of Copernicus model of the solar system What was his answer to the question Why do we not see stellar parallax Q5 List four of Galileo s observations that contradicted Greek Cosmology including the one which directly contradicted the Ptolemaic model Circle the one in complete contradiction to the Ptolemaic model Multiple Choice Questions 30 questions worth 1 mark each 30 marks Q6 Astronomy differs from the other physical sciences in that it deals with very large numbers which are cumbersome and difficult to handle its apparatus is extremely costly it assumes that the laws of physics hold at much larger time and distance scales than we have direct evidence for it uses much less mathematics relying instead on qualitative arguments Q7 Astronomy is important as a science because it allows us to test physical theories which are not testable in an earth based laboratory it generates funding for the less popular sciences such as nuclear physics it provides the sole method of accurate time keeping it attracts students into the physical sciences who would otherwise go into engineering 1 2 3 4 1 2 3 4 Q8 The steps in proper order of operation of the elementary scientific method are 1 proposal application for funding experiment publication 2 observation hypothesis prediction 3 funding proposal experiment publication 4 observation hypothesis prediction comparison of prediction to new observations to establish the hypothesis validity or not Q9 We have summer and winter seasons because 1 the Earth is closer to the Sun in the summer months the orbit is an ellipse 2 the Earth tips back and forth in space every year so that we are sometimes tipped towards the Sun sometimes away 3 the Earth is always oriented pretty much the same direction in space but our orbit around the Sun means that we are sometimes tipped towards the Sun sometimes away 4 the Moon s orbit influences the amount of sunlight falling onto the earth and it changes over the year Q10 On about September 23 the Sun was from our point of view 1 at its most southerly point 2 at its most northerly point 3 on the celestial equator and moving slowly north 4 on the celestial equator and moving slowly south Q11 An arc second is a measure of time interval between oscillations of a standard clock time interval between successive orbital position length along a circle 1 2 3 4 angle Q12 The Sun in its motion across the backdrop of stars moves along Q13 How much time will elapse before Polaris is at the celestial north pole again as a result of precession 1 2 3 4 the celestial equator the celestial poles the ecliptic the galactic plane 1 26 000 years 2 At least 1 million years 3 13 000 years 4 9 years Q14 The correct sequence for the appearance of the Moon s phases is 1 New Moon Waning Crescent First Quarter Full Moon 2 Waxing Crescent First Quarter Waxing Gibbous Full Moon 3 Full Moon Waxing Gibbous Last Quarter Waning Crescent 4 New Moon Full Moon Waxing Crescent Waning Crescent Q15 The motion of the Moon across the sky against the backdrop of stars is approximately 1 15 degrees per hour 2 1 degree per day 3 4 13 degrees per day its own diameter per day Q16 The motion of the Sun against the backdrop of stars is 1 15 degrees per hour toward the east 2 1 degree per day to the east except during retrograde phases when it is toward the west 3 15 degrees per hour toward the west 4 1 degree per day always eastward Q17 Which of the following lists places the actors on the stage of scientific discovery in the correct chronological order 1 Ptolemy Copernicus Newton Kepler Galileo Tycho 2 Ptolemy Copernicus Tycho Kepler Galileo Newton 3 Ptolemy Kepler Copernicus Tycho Galileo Newton 4 Ptolemy Copernicus Kepler Tycho Galileo Newton Q18 Aristarchus devised a method of estimating the relative distances of the Sun and Moon from Earth by 1 noting the size of the Earth s shadow on the Moon during a lunar eclipse 2 estimating the positions of the Moon and the Sun in the sky from different positions on Earth at the same time on the same day 3 noting the time of passage of the Moon from third quarter to first quarter 4 calculating their orbital radii from their orbital periods and using Kepler s law Q19 Retrograde motion of a planet is 1 westward against the stellar background 2 westward motion with respect to the foreground of the Earth 3 eastward against the stellar background 4 westward motion with respect to the foreground of the Earth Q20 The time when the Sun is furthest south of the celestial equator is 1 midnight 2 3 4 the summer solstice the winter solstice the spring equinox Q21 The sidereal period of a planet is 1 2 3 4 the time it takes the planet to return to the same position relative to the Earth the time it takes the planet to return to the same position relative to the stars as seen from Earth the time it takes the planet to return to the same position relative to the Sun as seen from Earth the time it takes the planet to complete one real side of its orbit comes from the words side and real Q22 The Ancient Egyptians predicted the flooding of the Nile River by noting the 1 position of the Sun s rising point along the horizon 2 heliacal rising of Polaris 3 heliacal setting of Polaris 4 heliacal rising of Sirius Q23 The Ancient Babylonians were able to predict eclipses 1 by noting the periodic nature of eclipses as described by the saros cycle 2 by shifting stones in periodic succession around the 56 Aubrey holes of a ziggurat 3 using the first and third of Kepler s laws 4 using a method first discovered by Thales of Miletus Q24 When we observe Saturn there are times when its rings cannot be seen at all because 1 they pass completely into the shadow of Saturn 2 they pass through the shadow of Jupiter the biggest planet 3 they are gaseous and they come and go depending on how close