Exam 1 Astronomy 100, Section 3 Select the most appropriate answer among the choices given. 1. This is exam A. Mark (A). 2. You observe the Moon setting at sunrise. Then the phase of the Moon must be (A) first quarter. (B) third quarter. (C) full. (D) new. (E) waxing crescent. 3. One light year is (A) the distance from the Earth to the Moon. (B) 1 million kilometers. (C) the distance light travels in one year. (D) the distance from the Earth to the Sun. (E) the time it take light to go around the Sun once. 4. If you wanted to find Jupiter in the night sky, you d look for it near (A) the ecliptic. (B) the celestial pole. (C) the celestial equator. (D) the zenith. (E) the horizon. 5. One astronomical unit (AU) is (A) the distance from Earth to the Moon. (B) 1 million kilometers. (C) 10 light years. (D) the distance from the Earth to the Sun. (E) the diameter of the Milky Way. 6. The Sun sets at different location along the western horizon each day because (A) the Earth is stationary. (B) the stars rotate with the celestial sphere. (C) the tilt of the Earth changes throughout the year. (D) the position of the Sun along the ecliptic is constantly changing. (E) the Sun always sets exactly due west. 7. An astronaut inside the Space Station experiences weightlessness because (A) there is no gravity in space. (B) gravity is extremely weak so far away from the Earth. (C) gravity of the Earth is canceled exactly by the gravity of the Space Station. (D) the Space Station has an anti-gravity device. (E) the Space Station is in a constant state of free-fall. 1
8. At which lunar phase(s) the highest high tides occur? (A) first quarter (B) new moon (C) full moon (D) both new and full moons (E) both first and third quarters 9. Which of the Galileo s discoveries challenged the belief that the Earth is the center of the Universe? (A) sunspots (B) moons of the Jupiter (C) phases of the Venus (D) all of above (E) only (B) and (C) 10. Why is a synodic month 2 days longer than a sidereal month? (A) Our calendar was invented too long ago and is no longer accurate. (B) The Earth travels about 30 degrees around the Sun in each month, and this adds 2 days between new moons. (C) One full Earth rotation takes less than 24 hrs, and it adds up to about 2 days in one month. (D) The Moon s orbit around the Earth is not perfectly circular. (E) The Earth rotation axis is tilted by 23.5 degrees. 11. Astronomers can measure what stars are made of by (A) seeing what spectral lines they show. (B) weight the light they emit. (C) measuring the speed of the light they emit. (D) weight them using Kepler s law. (E) measuring how fast they are moving. 12. Day and night are of equal length on or near (A) summer solstice. (B) winter solstice. (C) spring equinox. (D) fall equinox. (E) both (C) and (D). 13. While a 2-ton elephant was out for an evening walk at a speed of 5 miles per hour, a mice jumps out of the bushes and scares the elephant into a 15 miles per hour trot. How did the elephant s kinetic energy change? (A) kinetic energy increased by a factor of 3 (B) kinetic energy increased by a factor of 9 (C) kinetic energy decreased by a factor of 3 (D) kinetic energy decreased by a factor of 9 (E) kinetic energy did not changed 14. If the temperature of an object becomes twice as high, the wavelength where it emits the most amount of light becomes (A) 4 times longer. (B) 2 times longer. (C) the same. (D) 2 times shorter. (E) 4 times shorter. 2
15. Seasons are caused by (A) the change in Earth s distance from the Sun. (B) the Sun s changing brightness during the sunspot cycle. (C) one side of the Sun being cooler than the other. (D) Moon s shadow on Earth. (E) the Earth s rotation axis being tipped so that first one hemisphere and then the other receives sunlight more directly. 16. Lunar eclipse happens only during (A) full moon. (B) blue moon. (C) half moon. (D) crescent moon. (E) new moon. 17. If the radius of the Earth were to double with no change in its mass, your weight would (A) be unchanged. (B) 4 times larger. (C) be twice as large. (D) 1/2 as large as now. (E) 1/4 as large as now. 18. Which of the following is an example in which you are traveling at constant speed but not at constant velocity? (A) rolling freely down a hill in a cart, traveling in a straight line. (B) driving backward at exactly 50 km/hr. (C) driving around in a circle at exactly 10 km/hr. (D) jumping up and down, with a period exactly 60 hops per minute. (E) hanging by the edge of your seat, taking this exam. 19. Why does the length of day time change with season? (A) The Earth spins slower when it is hot outside. (B) The Earth spins slower when it is closer to the Sun. (C) When closer to the Sun, the Earth moves around the Sun at a higher speed because of stronger gravity. (D) The Earth rotation axis is tilted about the ecliptic. (E) The length of a day does not change, but the brightness of the Sun changes with season. 20. All of the following statements are true. Which one explains the reason why a solar eclipse does not occur at every new moon? (A) The nodes of the Moon s orbit precess with an 18-year period. (B) The orbital plane of the Moon is tilted by about 5 to the ecliptic plane. (C) The Moon rotates synchronously with its revolution about the Earth. (D) The sidereal month is shorter than the lunar month. (E) The Moon is the primary cause of tides on the Earth. 21. What is an epicycle supposed to explain? (A) Solar eclipses. (B) Seasons. (C) Precession. (D) Phases of the Moon. (E) Retrograde motion of the planets. 3
22. If the length of a year was 365.1 days, how often would we need a leap year? (A) 2 years (B) 4 years (C) 5 years (D) 6 years (E) 10 years 23. When a comet comes closer to the Sun, its orbital speed increases because (A) its angular momentum is conserved. (B) it gets too hot. (C) because it draws energy from the Sun. (D) Sun s tidal force shrinks it to a tiny snowball. (E) both (A) & (C) are correct. 24. At the Earth equator, the Sun is directly overhead (A) everyday. (B) once in a blue moon. (C) only once a month. (D) only twice a year. (E) at no time during a year. 25. We can see each other in the classroom right now because we (A) emit thermal radiation. (B) emit visible light. (C) emit infrared light. (D) reflect visible light. (E) reflect infrared light. 26. Radio waves differ from visible light in that they (A) travel much faster through empty space. (B) travel much slower through empty space. (C) have a much longer wavelength. (D) have a much shorter wavelength. (E) are not electromagnetic waves like light is. 27. (300) (2 10 4 ) is (A) 3 10 4 (B) 4 10 6 (C) 6 10 8 (D) 6 10 6 (E) 2 10 12 28. Which of the following never goes in retrograde motion? (A) Sun (B) Venus (C) Mars (D) Jupiter (E) Saturn 29. The force of gravity follows an inverse square law. This means that if the distance between two masses becomes twice as large, then the gravitational force between them (A) also becomes twice as large. (B) strengthens by a factor of 4. (C) weakens by a factor of 4. (D) weakens by a factor of 2. (E) is unaffected. 4
30. You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude? (A) The elevator is accelerating upwards. (B) The elevator is moving at a constant velocity upwards. (C) The elevator is accelerating downwards. (D) The elevator is moving at a constant velocity downwards. (E) Your diet is working. 31. From Kepler s third law, a hypothetical planet that is twice as far from the Sun as the Earth should have a period of (A) 1/2 Earth year. (B) 1 Earth year. (C) 2 Earth year. (D) 8 Earth year. (E) it depends on the planets mass. 32. The Greeks have considered a heliocentric system a plausible cosmological model, but they rejected it because (A) they could not feel the spin of the Earth. (B) they did not see the parallax of the stars. (C) they could not explain the phase of the Moon this way. (D) they did not think Gods would fling us off to a distant rock far away from the center. (E) it was just a bad outcome in a coin toss. 33. An example of discrete or spectral line radiation is (A) the northern light (aurora). (B) heat lamp at the lunch counter. (C) a plasma TV screen. (D) the sunset. (E) blue Moon. 34. Which of the following photons have the most energy? (A) X ray. (B) visible light. (C) infrared. (D) ultraviolet. (E) radio 35. The stars seen at night slowly change over the course of the year, this is because (A) the Earth rotates on its axis. (B) the Earth orbits about the Sun. (C) the Moon orbits the Earth. (D) the planets orbit the Sun. (E) You always see the same stars at night. Only your location on Earth matters. 5
36. Which of the following best describes the origin of ocean tides on Earth? (A) Tides are caused by difference in the force of gravity exerted by the Moon across the sphere of the Earth. (B) The Moon s gravity pulls harder on water than on land because water is less dense than rock. (C) Tides are caused by the tilt of the Earth s rotation axis. (D) Tides are caused primarily by the gravitational force of the Sun. (E) Tides are caused on the side of the Earth nearest the Moon because the Moon s gravity attracts the water. 37. Everything looks red through a red filter because (A) the filter emits red light and absorbs other colors. (B) the filter absorbs red light and emits other colors. (C) the filter transmits red light and absorbs other colors. (D) the filter reflects red light and transmits other colors. (E) your brain is tricked into thinking that everything should look red. 38. The amount of time between successive passes of the star Sirius across the meridian is (A) 23 hours 56 minutes. (B) 24 hours. (C) 365.25 days. (D) 12 years. (E) 26,000 years. 39. If the Moon is at first quarter tonight in Amherst, your buddy Mike in Australia will see the Moon tonight as (A) new. (B) first quarter. (C) full. (D) third quarter. (E) The Moon is not visible from the southern hemisphere. 40. Suppose you see two stars: a blue star and a red star. What can you conclude about the two stars? (A) The red star is more massive than the blue star. (B) The blue star is more massive than the red star. (C) The blue star is farther away than the red star. (D) The blue star has a hotter surface temperature than the red star. (E) The red star has a hotter surface temperature than the blue star. 41. If you drive south to Florida, you will see the North Star getting (A) higher in the sky. (B) lower in the sky. (C) brighter. (D) dimmer. (E) bluer. 42. A Pale Blue Dot refers to (A) Betelgeuse on the shoulder of Orion. (B) Venus seen in the morning light. (C) Earth seen from the Voyager space probe. (D) a supernova reported by ancient Chinese astronomers. (E) your face staring at this exam with sweaty palms. 6
43. Which of the following is the reason for a solar day being longer than a sidereal day? (A) precession of the Earth s axis. (B) the tilt of the Earth s axis. (C) the combined effect of the rotation of the Earth and its orbit about the Sun. (D) the Earth year being a non-integral number of Earth days. (E) the non-circular orbit of the Earth around the Sun. 44. Hydrogen has a spectral line emission at 486.1 nanometers. The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.1 nanometers. What can we conclude? (A) The star is getting hotter. (B) The star is getting colder. (C) The star is moving toward us. (D) The star is moving away from us. (E) The star has a planet around it. 45. The star Vega is about 3 times hotter than the Sun, so Vega must (A) be redder than the Sun. (B) be bluer than the Sun. (C) have the same color as the Sun but be brighter. (D) have the same color as the Sun but be dimmer. (E) be much larger than the Sun. 46. The Sun and Moon have nearly the same angular size as observed from Earth, but the Moon is about 400 times closer. From this we can conclude that the Moon s diameter is (A) nearly the same as the Sun s diameter. (B) about 400 times larger than the Sun s diameter. (C) about 400 times smaller than the Sun s diameter. (D) about 400 2 times larger than the Sun s diameter. (E) about 400 2 times smaller than the Sun s diameter. 47. At the South Pole, (A) stars neither rise nor set during the night. (B) only the constellations of the zodiac are visible. (C) the Sun rises twice a day. (D) Polaris circles the sky near the horizon. (E) a flagpole will not cast a shadow at noon. 7
48. A skater can spin faster by pulling in his arms closer to his body or spin slower by spreading his arms out. This is explained by (A) the law of gravity. (B) Newton s third law. (C) conservation of momentum. (D) conservation of angular momentum. (E) conservation of energy. 49. The large black spot seen on the surface of the Earth during the solar eclipse is (A) a black hole. (B) the shadow of the Moon. (C) the shadow of the Sun. (D) an fire storm ignited by the Sun. (E) a worm hole. 50. One of the lecture demos you saw was the table cloth pulling trick. Your professor yanked the table cloth out without pulling and breaking the plate, wine glass, or the crystal candle holder. The reason why they did not fall down and crash on the floor is that all of those objects have certain amount of (A) inertia. (B) angular momentum. (C) magnetic field. (D) energy. (E) magic. 8