PHYS 160 Astronomy Test #1 Fall 2017 Version B

Transcription

1 PHYS 160 Astronomy Test #1 Fall 2017 Version B 1

2 I. True/False (1 point each) Circle the T if the statement is true, or F if the statement is false on your answer sheet. 1. An object has the same weight, but a different mass on different planets. 2. A Light-year is a unit of time. 3. A lunar eclipse can only occur during the new phase. 4. The northern hemisphere of Earth experiences Summer when the Earth is at aphelion. 5. The planets orbit the Sun at constant speeds. 6. The position of the North Celestial Pole is currently near the bright star Polaris. 7. Our solar system has a diameter of 1 light year. 8. The Sun follows the path of the celestial Equator throughout the year. 9. The name of our galaxy is The Milky Way 10. If the angular diameter of an object can be measured, and the distance to that object is known, then the true physical diameter can be calculated. II. Definitions (1 point each). There are 10 definitions given. Select the word or phrase that best matches the definition from the table of words below. Put your answer on the answer sheet. Note, there are more words than there are definitions, so not all of them will be matched. perihelion celestial sphere geocentric universe aphelion azimuth ecliptic parallax epicycle acceleration retrograde zodiac prograde zenith right ascension declination astronomical unit altitude diurnal motion eccentricity heliocentric universe equinox lightyear parsec solstice 1. A change in the direction or magnitude of velocity divided by the change in time. 2. In the geocentric universe, a moving circle about which planets revolve. 3. The angle of an object s position above the horizon. 4. The point in its orbit where a planet is farthest from the Sun. 5. The annual path of the Sun, relative to the stars on the Celestial Sphere; the plane of earth s orbit around the Sun. 6. The coordinate on the celestial sphere exactly analogous to Earth s longitude, measured in hours, minutes, and seconds from the vernal equinox. 7. The apparent backwards motion of a planet with respect to the fixed background stars. 8. A band of 13 constellations around the sky through which the Sun appears to move throughout the year. 9. A measure of the flatness of an ellipse; a measure between 0 (circle) and 1 (flat line). 10. A description of the cosmos where the Earth is at the orbital center of all celestial bodies. 2

3 III. Multiple Choice (1 point each) Select the letter next to the best answer for each question. Circle the letter on your answer sheet. 1. What basic shape do stars seem to trace in the northern sky if you watch (or do a time-lapsed photograph) over the course of an evening? a. circles, with the north celestial pole at the center. b. spirals, as the star moves while Earth rotates. c. straight lines d. ellipses, with the north star at one of the focal points. 2. During a solar eclipse, a. The Sun comes between the Earth and the Moon b. The Moon comes between the Earth and the Sun c. The Sun goes below the horizon d. Earth comes between the Sun and the Moon. 3. The ecliptic and celestial equator intersect at two points called the a. equinoxes b. solstices c. tropics d. sidereal points e. poles 4. Who came up with a hybrid model that was partly geocentric and partly heliocentric? a. Ptolemey b. Copernicus c. Tycho Brahe d. Galileo 5. The 4 largest moons of Jupiter were first discovered by which of the following scientists? a. William Herschel b. Johannes Kepler c. Tycho Brahe d. Isaac Newton e. Galileo Galilei 6. From any location upon Earth, the zenith defines a direction a. vertically above the North Pole. b. vertically above an observer. c. toward the Sun at noon. d. vertically above a point on the equator. 3

4 7. In ancient times, people distinguished the planets from the stars because a. planets appear much brighter than stars b. features on planet surfaces could be seen whereas no star s features could be seen. c. planets move relative to stars d. planets differ in color from the stars e. planets can be seen during the day 8. An arc minute is a. a measure of how far the Sun moves during one minute b. one-sixtieth of a degree c. how far the Earth turns on its axis in one minute d. 60 degrees e. the angular diameter of the Sun 9. How long will a lunar day be, at a location on the Moon s equator? a. About 28 days because the Moon rotates once per orbit around the Earth. b. Infinite. The Sun never appears to rise and set because the Moon does not rotate. c. 1 year because the Moon rotates to keep one face towards the Sun. d. depends on the phase of the Moon 10. When the Sun is at one of the equinoxes, a. day and night are of equal length only for people on the equator. b. the day is longer than the night in one hemisphere of Earth and shorter in the other hemisphere. c. people on the equator have perpetual daylight. d. day and night are of equal length everywhere on Earth. 11. A full moon always rises at approximately what time of day? a. sunset b. sunrise c. midnight d. noon e. depends on the time of year 12. If you are standing at Earth s North Pole, which of the following is directly overhead? a. celestial equator b. ecliptic c. zodiac d. polaris e. the Sun 4

5 13. In Antartica (South Pole), the longest period of daylight occurs in a. March b. June c. September d. December 14. Kepler's laws apply to the motion of a. the planets around the sun b. binary stars c. Earth satellites d. all of these e. none of these 15. According to Newton s First Law, a. an applied force always causes a change in velocity of the object b. an applied force always causes a change in position of the object c. the larger the force on an object, the larger the change in the rate of velocity of that object. d. if no unbalanced force is acting on an object, the object s speed and direction will remain constant. 16. Polaris is unique because a. it moves in a different direction than any other bright star b. it is the brightest star in the sky c. it twinkles more than any other bright star d. it is fairly bright and shows very little motion when viewed from Earth e. The premise is false. Polaris is not unique at all. 17. Ptolemy's theory placed the Earth a. at the center of the universe b. at the center of the solar system, but far from the center of the universe c. in orbit around the sun d. in orbit around the moon e. none of the above 18. The Sun s apparent path is a. always south of the celestial equator b. right on the celestial equator c. always north of the celestial equator d. is south of the celestial equator for part of the time and north of the celestial equator for part of the time. e. crosses the north celestial pole once per year. 5

6 19. To measure the position of a star on the celestial sphere, we use the coordinates a. latitude and longitude b. celestial latitude and celestial longitude c. right ascension and declination d. equinox and solstice e. prograde and retrograde 20. we would expect an eclipse at every full moon and new moon if a. the moon had a larger orbit around the Earth b. the Earth had a larger orbit around the sun c. the moon's orbit around the Earth were perpendicular to the Earth's orbit around the sun d. the plane of the moon's orbit around the Earth coincided with the plane of the Earth's orbit around the sun 21. Which of the following is not true about the ecliptic? a. It is the path taken by the Moon as it orbits the Earth. b. It passes through the constellations of the zodiac. c. It is the plane in which the Earth orbits around the Sun. d. It forms a circle on the celestial sphere that is inclined at an angle of 23.5 degrees to the celestial equator. e. It is the apparent path through the sky taken by the Sun over the course of a year. 22. If the Earth s rotational axis were not tilted with respect to the ecliptic plane, a. the daylight period on Earth would be the same year-round b. there would be no seasonal variations on Earth. c. Earth s poles would not experience 6 month-long nights d. all of the above 23. What was the greatest contribution of Tycho Brahe to astronomy? a. He developed a Sun-centered model of the universe b. he was the first to use a telescope to make astronomical observations c. he proposed some simple laws to describe the motion of planets and other objects d. he determined that the planets orbit the Sun in elliptical orbits e. he amassed a large number of precise measurements of stellar and planetary positions. 24. When the moon is between the sun and the Earth, we call its phase a. full moon b. last quarter c. new moon d. you can't fool me; the moon can never get between the sun and the Earth 6

7 25. The most useful distance measurement unit to describe the distance between the Sun and each planet is a. the lightyear b. meters c. kilometers d. parsecs e. astronomical units 26. If the mass of the Sun were doubled, the force of gravity between the Sun and Earth would a. stay the same b. be 4 times larger c. be 4 times smaller d. be 2 times larger 27. Modern scientists now know that the nightly motion of stars and planets in our night sky is caused by a. the revolution of the Earth around the Sun. b. the rotation of the entire celestial sphere around the Earth c. the rotation of the Earth on its axis. d. the motion of the solar system around the galaxy. 28. Before the invention of the telescope, the known planets were a. Mercury, Venus, Mars, Jupiter, and Saturn b. Mercury, Venus, mars, Uranus, and Neptune c. only Venus, Mars, and Jupiter d. Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto 29. How much of the total surface of the Moon is illuminated by the Sun in 1 st quarter phase? a. one quarter b. one half c. all of it d. none of it 30. Assuming clear skies everywhere, a total solar eclipse is visible a. to people anywhere in the sunlit hemisphere of Earth b. to everyone on Earth c. only to people in a circular area on Earth having a diameter equal to the diameter of the Moon d. only to people in a long narrow path much smaller than the hemisphere. 7

8 IV. Short Answer Questions Answer any five (5) of the following questions. Each question is worth 10 points. Answers may contain paragraphs, lists, and drawings. Please put your answers on the white paper provided. 1. Describe how solar and lunar eclipses occur. Why do we not see eclipses twice per month? Which kind of eclipse are you more likely to see from our location in a given year 2. Describe what you might see in the night sky if you are in a dark location in central Arkansas facing north and you observe for several hours. 3. Explain the statement: The farther away we look in distance, the further back we look in time. 4. How do the following motions affect the position of objects in our sky: Earth s rotation on an axis defined by the north and south poles, Earth s rotation around the Sun, the rotation of the Moon around the Earth, precession? 5. Is the far side of the Moon the same as the dark side of the Moon? Explain. 6. What is meant by a geocentric universe? Name the three scientists who played the primary roles in overturning the geocentric viewpoint. Describe their main contributions to astronomy. 8