Multiple Choice (circle correct answer):

1. The gnomon (or style) of an equatorial sundial represents the Earth's [axis, Equator].

   axis

2. The dial plate of an equatorial sundial represents the Earth's [axis, Equator].

   Equator

3. The upper dial face of an equatorial sundial represents the [Northern Hemisphere, Southern Hemisphere].

4. The lower dial face of an equatorial sundial represents the [Northern Hemisphere, Southern Hemisphere].

5. The 12 o'clock noon hour line (also known as the meridian line) that divides the dial face in half represents your [line of latitude, line of longitude].

6. Relative to a horizontal surface, the gnomon of an equatorial sundial should be inclined at an angle equal to your [latitude, longitude].

7. Relative to a horizontal surface, the dial plate of an equatorial sundial should be inclined at an angle equal to the [complement, supplement] of your latitude.

8. [Complementary, Supplementary] angles are two angles for which the sum of their degree measurements equals 90 degrees.

9. As viewed from above the North Pole, the Earth appears to rotate [clockwise, counterclockwise]. (If necessary, experiment with a globe before answering this question.)

10. As viewed from above the South Pole, the Earth appears to rotate [clockwise, counterclockwise]. (If necessary, experiment with a globe before answering this question.)

11. Sun shadows fall in the [same, opposite] direction as the Sun.

12. During the day, the gnomon shadow appears to move [clockwise, counterclockwise] around the [upper, lower] dial face.

13. The Earth's [rotation, revolution] causes the gnomon shadow to appear to move around the dial face.

14. The Earth's [rotation, revolution] causes the gnomon shadow to move from the upper dial face to the lower dial face, and vice versa.

15. When Daylight Saving Time is in effect, Solar Time (sundial time) is [earlier, later] than Standard Time (wristwatch time). Hint: Remember the mnemonic, "Spring forward; fall back."

Short Answer (be clear and concise):

1. When doesn't an equatorial sundial work?
   
   
   
2. On the day of the Equinoxes (MAR 20, SEP 22), the gnomon (or style) of a properly oriented equatorial sundial will not cast a shadow on the dial plate. Explain.
   
   
   
3. The Earth rotates once every 24 hours (approximately). How many degrees does the Sun appear to move across the sky in one hour? In four minutes? Hint: One complete rotation of the Earth is 360 degrees.
   
   
   
4. Why do time zones generally run north-south instead of east-west? Why are time zones 15 degrees of longitude in width?
   
   
   
5. The Sun and Earth are parts of an interconnected system. Use the words "rotation" and "revolution" to summarize your short-term (daily) and long-term (annually) observations of the equatorial sundial.
   
   
   

For Further Thought:

1. Why is "clockwise" clockwise?
   
   
   
2. Time is equivalent to longitude. Explain. What would be the time difference between two cities separated by 45 degrees of longitude?
   
   
   
3. What would be the effect of misaligning the sundial so that the dial face is inclined at an angle less than the complement of your latitude?
   
   
   
4. What would be the effect of misaligning the sundial in the north-south direction? For example, if 12 Noon actually pointed toward the northeast rather than true north, would sundial time read earlier or later than the actual time?
   
   
   
5. Does an equatorial sundial work the same north and south of the Equator?