Review Questions: Earth’s Motions
1. What unit of distance is defined as the average distance between Earth and sun?
2. What unit of distance is equal to about 9.5 trillion km?
3. What unit of distance is about the same as 3.26 light-years?
4. Describe Earth’s shape compared to a sphere.
5. What shape are the orbits of all planets and moons?
6. What is the name of the star nearest to Earth?
7. How many stars are in the solar system?
8. Where is over 99% of the solar system’s mass?
9. What is the name of the 2nd nearest star to Earth?
10. Virtually all the stars we see without a telescope are bound together by gravity in a large group called what?
11. What is the Local Group?
12. What is a supercluster to astronomers?
13. What is between stars and galaxies?
14. How is rotation different from revolution?
15. In which compass direction does Earth rotate?
16. In which compass direction do shadows point in the morning?
17. What time of day are shadows the longest?
18. In which direction to shadows move as the day progresses?
19. What 2 things work together to cause the seasons?
20. What is precession?
21. How far is the Earth’s axis tilted from “vertical” (as defined by the plane of Earth’s orbit around the sun)?
22. Describe day and night on the north pole over the course of a year.
23. What is the longest day of the year called?
24. What is the shortest day of the year called?
25. Name one day of the year when the length of day and night are the same. Be specific.
26. Name the other day when day and night are the same length.
27. What is perihelion?
28. Why is the equator warmer than the north pole in summer, even though the sun’s up for 6 months straight, 24/7, at the pole, and it’s dark all night at the equator?
29. Why is South America warmer in January, and cooler in July?
30. Where on Earth can the sun be see straight up in the sky at noon at least one day each year?
31. Where on Earth could you experience at least one day each year when the sun never rises?
32. What is the name of our supercluster?
33. What is the latitude of the equator?
34. What is the latitude of the Tropic of Cancer?
35. What is the latitude of the South Pole?
36. What is the latitude of the Antarctic Circle?
37. What is the latitude of the Tropic of Capricorn?
38. What is the latitude of the Arctic Circle?
39. What aspect of time is based on Earth’s rotation?
40. What 2 aspects of time is based on Earth’s revolution?
41. What aspect of time is based on the moon’s revolution?
42. How long does it take for the Earth to complete 1 complete rotation?
43. How long does it take for the Earth to complete 1 complete revolution?
44. Earth’s period of revolution is not exactly 365 days, it’s actually closer to 365 ¼ days. How do we account for the extra ¼ day?
45. Actually, Earth revolves once in 365.24 days, not 365.25 days. How do we deal with this discrepancy?
46. How many major planets are there in our solar system?
47. How far is it to Proxima Centauri?
48. If you could travel to the moon in 4 hours, how long would it take to reach Proxima Centauri?
49. How many stars are thought to be in the Milky Way galaxy?
50. How many galaxies are thought to exist?
51. Why was Polaris not the ancient Egyptian’s north star?
52. How long does it take the sun to revolve around the center of the Milky Way?
53. If you were at the North Pole in winter and you looked straight up at noon, what would you see?
54. If you were at the North Pole in summer during a total solar eclipse and you looked straight up at noon, what would you see?
55. During what season is Earth closest to the sun?
56. Some light from the sun left the sun’s surface on the day you were born. How far has that light travelled since then?
57. If someone on a planet 100 million light years away was looking at Earth right now with an extremely good telescope, what would they see on Earth’s surface?
58. Name the 4 inner planets in order from the sun.
59. Name the 4 outer planets, starting from the one closest to the sun.
60. Name 3 specific objects in the solar system that aren’t the sun or a major planet.
61. How many times does Earth rotate in one revolutionary period?
1. astronomical unit
4. kind of a squashed sphere, an oblate spheroid
6. the sun
7. one (the sun)
8. the sun
9. Proxima Centauri
10. The Milky Way galaxy
11. the group of about 20 galaxies “near” and including the Milky Way
12. a cluster of galaxy clusters
13. almost nothing (that we can see, at least)
14. rotation is spinning on an axis, revolving is one body orbiting another
15. toward the east
17. just after dawn and just before sundown
19. the tilt of Earth’s axis as it orbits the sun
20. the slow wobble of Earth’s rotational axis
22. 6 months of daylight (summer), one day of 1/2 day and 1/2 light (autumnal equinox), then 6 months of night (winter), then another 1/2 and 1/2 day (vernal equinox)
23. summer solstice
24. winter solstice
25. vernal equinox
26. autumnal equinox
27. the point closest to the sun in a planet’s orbit
28. sunlight is much more direct at the equator than it is at the poles
29. the southern hemisphere is tilted toward the sun in Jan. and away from the sun in July
30. between the tropics of Capricorn and Cancer
31. north of the Arctic circle and south of the Antarctic circle
32. Virgo Supercluster
34. 23.5° North
35. 90° South
36. 66.5° South
37. 23.5° South
38. 66.5° North
39. day/night cycle
40. years and seasons
42. 24 hours
43. 1 year
44. leap day every 4 years
45. skip a leap year every century
47. 4.3 ly
48. 11,000 years
49. 100-400 billion
50. 100- 200 billion
52. about 250 million years
56. 11 ly if you’re 11 years old
58. Mercury, Venus, Earth, Mars
59. Jupiter, Saturn, Uranus, Neptune
60. any moon, minor planet, comet, Kuiper belt object, or asteroid you can name
61. 365.2422 times