Astron 100 Sample Exam 1 1. Solar eclipses occur only at (A) New moon (B) 1 st quarter moon (C) Full moon (D) 3 rd quarter moon (E) The equinoxes 2.

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1 Astron 100 Sample Exam 1 1. Solar eclipses occur only at (A) New moon (B) 1 st quarter moon (C) Full moon (D) 3 rd quarter moon (E) The equinoxes 2. If the Moon is at first quarter tonight in Amherst, tonight for people in Australia, 180 degrees of longitude away, the Moon will be (A) New (B) 1 st quarter (C) full (D) 3 rd quarter (E) The Moon isn t visible from the Southern hemisphere. 3. The Sun s declination on March 21 st is (A) degrees (B) 0 degrees (C) degrees (D) unknown, it depends on where you are on Earth. 4. Which of the following is the reason for the solar day being longer than a sidereal day? (A) Precession of the Earth s axis (B) The tile of the Earth s axis (C) The Earth year being a non-integer number of Earth days (D) The non-circular orbit of the Earth around the Sun (E) The combined effect of Earth s rotation and its orbit about the Sun 5. The gravitational force between two objects, each with a mass of 1 kilogram, is weaker when both objects are (A) Made of low density materials (B) Separated by great distances (C) Spinning more slowly (D) Distant from any star (E) All of the above. 6. You observe the Moon setting at sunrise, therefore the phase of the Moon must be (A) First quarter (B) Third quarter (C) Full (D) New (E) Any of the above. The Moon always sets at sunrise. 7. The Sun is located (A) At one focus of the Earth s circular orbit (B) At the exact center of the Earth s circular orbit (C) At the exact center of the Earth s elliptical orbit (D) At one focus of the Earth s elliptical orbit 8. When you see the Full Moon, where did the photons come from that you are observing? (A) Thermal emission from rocks heated by sunlight. (B) Sunlight reflected off the Moon s surface (C) Spectral line emission from a thin layer of gas over the Moon s surface (D) The hemisphere of the Moon that is covered with white phosphorescent rocks. (E) Light from Earth bouncing back from the Moon.

2 9. If you see a crescent Moon early in the evening, how long will it be until there s a Full Moon? (A) About 6 hours (B) About 3 days (C) About 2 weeks (D) About half a year 10. The equation p 2 =a 3 tells us that (A) The parallax of a star increases in proportion to its angular shift (B) The power output of a star grows larger with its surface area (C) The period of a planet s orbit is larger when its orbit is bigger (D) The number of protons in a nucleus is 2/3rds the atomic number (E) The pressure grows larger in proportion to the area over which it is applied. 11. According to the heliocentric model, when Mars undergoes retrograde motion it (A) Rises in the West and sets in the East (B) Changes from a counterclockwise to a clockwise orbit around the sun (C) Changes from a clockwise to a counterclockwise orbit around the sun (D) Is being passed the Earth, which is in a faster orbit (E) Begins traveling on an epicycle instead of an orbit 12. For most of history, the lack of observable stellar parallax was interpreted to mean that (A) Larger telescopes were needed (B) Stars are too far away for parallax to be measured (C) Earth is stationary (D) The Sun is at the center of the universe (E) Astrological horoscopes could predict our future 13. Which of the following statements about celestial coordinates is correct. (A) Declination is measured in degrees, north or south of the celestial equator. (B) Right ascension is measured in hours on the celestial equator, starting from the vernal equinox. (C) Declination is analogous to latitude in geographic coordinates. (D) Right ascension is analogous to longitude in geographic coordinates. (E) All the above statements are correct. 14. Suppose that the Earth reversed its direction of spin, without changing its orbital direction around the Sun. Which of the following would be true? (A) The Sun would rise in the west and set in the east. (B) The Sun would appear to travel in the opposite direction along the ecliptic. (C) The sidereal day would be shorter than the mean solar day. (D) All of the above. 15. Which of the following provides evidence that the Moon causes ocean tides? (A) Because they are higher at night (B) Because the water is high only when the Moon is high above the horizon (C) Because the Moon-rise and the tide pattern repeat 50 minutes later every day (D) Because high tide occurs whenever the Moon is full. 16. The time between successive sunrises on the Moon is. (A) 18.6 years (B) 27.3 days (C) 29.5 days (D) 50 minutes

3 17. used the extensive records of planetary positions measured by to discover that the orbits of the planets are. (A) Tycho Brahe, Nicolas Copernicus, circular (B) Johannes Kepler, Tycho Brahe, elliptical (C) Isaac Newton, Galileo Galilei, elliptical (D) Ptolemy, Aristotle, circular 18. In what kind of units would we measure a semi-major axis? (A) Temperature (B) Period of revolution (C) Distance (D) Angle (E) Miles per hour 19. Which of the following telescopic observations was the most crucial contribution of Galileo in rejecting the geocentric system? (A) The observation of parallax (B) The fact that Venus shows both crescent and gibbous phases (C) The fact that no epicycles could be seen between the planets. (D) His discovery of spots on the Sun (E) All of the choices are correct. 20. Which of the following would you expect to observe during the December solstice in Australia? (A) Nights are longer than daylight. (B) The Sun is relatively close to the horizon around noon. (C) Cold weather (D) Sun rises southeast (E) All of the above. 21. When would you expect to see the Moon near the North Star? (A) The full Moon of the winter solstice (B) The full Moon of the summer solstice (C) Any phase around the equinoxes (D) Never 22. The Earth s radius is about 6400 km. Communications satellites orbit the Earth at a distance about 7 farther away from the center of the Earth. The gravitational force they feel at this distance is (A) zero. (B) 7 larger than at Earth s surface. (C) 7 smaller than at Earth s surface. (D) 49 larger than at Earth s surface. (E) 49 smaller than at Earth s surface. 23. 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

4 24. Which phase of the Moon do you expect to see rising just before dawn? (A) Waxing gibbous (B) Waxing crescent (C) Waning crescent (D) Waning gibbous 25. If the Moon sets at 10:00 a.m. today, approximately what time will the Moon set tomorrow? (A) 10:00 p.m. (B) 4:00 p.m. (C) 10:50 a.m. (D) 10:04 a.m. 26. Which of the following is true during the equinoxes? (A) The Moon is on the celestial equator (B) The Sun is on the celestial equator (C) The planets rise due east and set due west (D) All of the choices are correct. 27. Why do the constellations that are visible in the sky at night change with the seasons? (A) Because the celestial sphere revolves around the Earth (B) Because the Earth is a sphere (C) Because the Earth rotates about an axis (D) Because the Earth revolves around the Sun 28. Which of the following statements regarding the motions of objects on the celestial sphere is true? (A) The Sun moves along the celestial equator (B) The Moon moves along the celestial equator (C) The planets move parallel to the celestial equator (D) The stars move through the zodiac (E) None of the above. 29. Suppose that an asteroid is orbiting the Sun, on an elliptical path which ranges from 0.5 AU to 1.5 AU from the Sun. How long does it take the asteroid to complete one orbit around the Sun? (A) 1 Earth years (B) 2 Earth years (C) 4 Earth years (D) 8 Earth years 30. The apparent motion of the planets is in a narrow band on the celestial sphere called. (A) the celestial equator (B) the Milky way (C) the constellations (D) the zodiac 31. The acceleration of gravity on the Moon is 1/6 th of that on Earth. A Moon rock has a mass of 2 kg. What is the mass of the same rock when brought to Earth? (A) 2 kg (B) 12 kg (C) 6 kg (D) 1/3 kg 32. Which of the following is experiencing the Earth s gravitational force? (A) A boat floating in water (B) An airplane taking-off (C) A skydiver falling under the force of gravity (D) An astronaut aboard the space station. (E) All of the choices are correct.

5 33. The Earth s shape is somewhat flattened, so that the diameter through the poles is shorter than the diameter of the equator. Where would you weigh more? (A) At the poles (B) At the equator (C) My weight is the same everywhere. 34. Suppose that the Sun started shrinking in size, without losing any mass. What would be the effect of the Sun s change on the orbits of the planets? (A) The orbits would become smaller in size. (B) The orbits would become larger. (C) The orbits would not be affected. (D) The planets would escape. 35. When a bus makes a sudden stop the passengers lurch forward as a consequence of law. (A) Newton s 1 st Law (of inertia) (B) Newton s 2 nd Law (F = ma) (C) Newton s 3 rd Law (action and reaction) (D) Newton s Gravitational Law 36. From Earth the Sun s angular diameter is about 30 arcminutes. If we lived on Mercury, about three times closer to the Sun, the Sun s angular diameter would be about (A) 3 arcminutes (B) 10 arcminutes (C) 90 arcminutes (D) 270 arcminutes 37. An astronomer measures the optical brightness of two stars. Star A is 9 times brighter than Star B. Therefore, the astronomer can conclude (A) Star A is 9 times closer than Star B (B) Star A is 3 times farther than Star B (C) Star A is 3 times closer than Star B (D) Choice A, but only if Star A and Star B are the same kind of star (E) Choice B, but only if Star A and Star B are the same kind of star (F) Choice C, but only if Star A and Star B are the same kind of star 38. Star A s parallax is 10 times larger than Star B s. Therefore Star A must be 10 times than Star B. (A) farther away (B) nearer (C) larger (D) smaller (E) more massive

6 39. Short answer: Sketch the arrangement of the Earth, Moon, and Sun, for the 1 st quarter moon, as seen from above the Earth. Label the Sun S, the Earth E and the Moon M. Shade the dark side of the Earth and Moon. 40. Short answer: Make a sketch showing the orbits of Earth and Mars and show how the heliocentric model explains retrograde motion of Mars as seen from the Earth by drawing the Earth and Mars at several points in their orbits.