Geography 12
Worksheet 3.1
Chapter 3 Objectives:

The Earth In Motion
Read pages 38 – 43 of Planet Earth: A Physical Geography. Answer
the following questions:
Vocabulary (1 mark each)
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

Revolution: the earth orbiting the sun

Aphelion: the point in the orbit of the earth where it is farthest from the
sun

Perihelion: the point in the orbit of the earth where it is closet to the sun
Describe the major
motions withing the
universe
Describe the different
motions of the earth in
space
Identify the effects of
these motions on the
physical geography of
the planet
Relate to rotation of the
earth to the need for time
zones
Begin to appreciate the
interrelationships
between the various
physical processes and
systems operating on the
earth
Precession of the Equinoxes: means that the position of the equinoxes is
changing slowly with respect to the background stars
Eccentricity: the measure of the elliptical orbit of the earth
Equinoxes: the two times each year when the sun shines equally on both northern and
southern hemispheres (spring and autumn)
Solstice: the time each year when the sun shines directly over the Tropic of Cancer or
the Tropic of Capricorn (summer in the North, summer in the south)
Short Answer (2 marks each)
1. Describe the Earth’s place in the Milky Way in terms of distance from the galactic
center. How long would it take a person to travel to the center of the galaxy if
they could travel at the speed of light, assuming the distance is 25,000 light years
away? How many kilometers would that person have traveled?(one light-year is
equal to 9,500,000,000,000 kilometers)
- 25000 years to travel the distance
- 9,500,000,000,000 * 25,000 = 237,500,000,000,000,000 kms
2. When is the earth at it’s aphelion? ___January 3
When is the earth at it’s perihelion?___July 4
3. Explain how the earth experiences eccentricity of its orbit around the sun and
what effect it has on the solar heating of the earth.
Over 100,000 years, the earth’s orbit changes from more circular to more elliptical and
back again. When the orbit is more circular, the solar heating is more evenly spread
over the earth (less contrast in temperature)
4. Briefly describe why we have more distinct seasons in Canada compared with
lower latitude places such as Mexico.
Due to the earth’s axis, we experience less sun(and less concentrated sunshine) in the
winter than Mexico and therefore more distinct seasons.
5. What is the “wobble” and how does the “wobble” in the axis affect seasonal
temperatures?
The earth’s angle of tilt from the plane of the elliptic varies from 21.5 to 24.5 degrees
over the course of about 40,000 years. When the tilt is greatest, the earth’s winters are
coldest and summers are hottest. When the tilt is less, there is less difference between
summer and winter.
6. (4 marks)
a. Draw a simple sketch map to show the area of the northern hemisphere
that can be called the “land of the midnight sun”.
b. Explain why this area can boast of such a phenomenon.
c. Why des this phenomenon help explain the great contrasts in temperature
between winter and summer at such high latitudes?
d. Copy and paste a promotion from the internet from a city, town or
company that uses the “land of the midnight sun” to attract tourists or
business.