NAME: _____________________________ PERIOD: ___________
Lesson: Earth’s Rotation
Objective: How do we use Earth’s motion to determine the length of a day?
The Earth spins once a day on its axis, which is called one rotation. The axis is an imaginary line going
from the North Pole to the South Pole through the Earth’s center. If you were above the North Pole
looking down on Earth, the Earth’s rotation is counterclockwise, or from west to east. It is this east-west
rotation that makes all objects in the sky appear to move from east to west.
DO NOW: Define the following terms:
1. Rotation: ______________________________________________________________________
2. Sidereal Day: ___________________________________________________________________
3. Solar Day: ______________________________________________________________________
4. Zenith: ________________________________________________________________________
1. Complete the “Do Now”.
2. Instructor will provide a brief presentation on Earth’s rotation.
3. If further review is required at home, see the link on the homework page at
http://johnbowne.org/apps/classes/ under the science section.
4. Using the information in the presentation, complete the questions in the following section.
5. Review the questions using your notes and with your group.
6. Upon completing all questions, instructor will provide a summary on all questions.
1. How many degrees does the Earth spin in one hour? Show calculations.
2. How do we measure the length of a “true day” (from when to when)?
3. As the Sun travels across the sky from East to West, what direction does the shadow cast by a
pole move across the ground?
4. At noon, what general direction does a shadow cast by a pole point?
5. At which time of day is the length of shadows the longest?
6. At which time of day is the length of shadows the shortest?
7. What is the angle formed by two shadows cast one hour apart? How did you determine this?
8. Is there ever a time when the vertical pole will cast no shadow because the Sun is directly
overhead at noon in the continental United States?