Exploring the Astronomy of the Seasons
3: Modeling the Seasons
#3 of Reasons for Seasons)
Students explore a model of the Earth’s daily rotation and
annual revolution around the sun; they try to puzzle out at which
point each season occurs in their part of the world.
Prepare a simulation of the earth-sun system by placing a lamp
on the floor to represent the sun. Use a globe to represent the
earth, which will spin (rotate) on its axis and revolve around
the sun. Cut a star shape out of paper, label it the North Star,
and place it on the board. Orient the North Pole of the globe
so it points toward it. Finally, place 4 Xs of masking tape on
the floor on each side of the lamp, but don’t tell students
which season each represents.
Ask a student to find your city or state on the globe and tape
a small paper circle on it. Challenge them to keep an eye on this
location – and the light it receives – as they explore
how the Earth and sun interact!
the terms rotation and revolution.
Have a volunteer demonstrate rotation with his or her body and then
with the globe. (You might reveal that spinning is another word for
rotation.) Once they do so, let them know that the Earth rotates counterclockwise
on its axis and have a volunteer demonstrate this. Ask students to notice
what happens to the light hitting your school location. Ask, What
do you think each rotation represents? Explain your thinking. (Each
represents a 24-hour day during which every location has daylight and
- Ask another
volunteer show how the earth moves (revolves) around the sun (also counterclockwise).
Explain that the Xs represent different seasons and that the Earth is
not up and down on its axis, but always tilted (23.5 degrees) with the
North Pole facing the North Star at all times. As the student walks
around the sun slowly to represent the Earth’s revolution, remind
him or her to spin the globe quickly to also represent days passing.
Ask, What do you think one complete revolution represents?
(A year or 365 ¼ days.)
a volunteer to stand at one of the Xs and rotate the earth to show two
days coming and going. Have another student take the globe and move
counterclockwise to the next X and do the same, and so on with each
season. Remind them to keep the North Pole pointing to the North Star
as they revolve around the sun from season to season. As they do so,
ask students to pay close attention to the sun's relationship to their
hometown during each season.
small groups to discuss which X they think is which season. You might
prompt them to focus on their hometown and discuss characteristics of
each season there: temperature, sunlight, and so on. They may want to
again examine the relationship between their hometown circle and the
lamplight on the globe. Also share this clue with them: the first days
of spring and fall are called the equinox, which is related
to the word equal.
- Have each
group write a label for each of the four seasons and place the labels
face down on what they think is the appropriate X. Then season by season,
turn over the labels and ask each group to explain its thinking. Conflicts
in labels should spark fertile discussions! Rather than confirm answers
at this point, you might want to conduct the next couple of activities
and revisit students’ ideas at the end. Alternatively, you can
pass out and discuss the Earth,
Sun, and Seasons drawing.
Consider setting up a model of the Earth's annual revolution around the
sun in the classroom and keep it active all school year. Put the sun in
the center and create an Earth with the proper tilt. Mark a pathway the
Earth will follow on its 360 degree revolution. mark both equinoxes and
solstices along the path. Try to make the model large enough so each week's
changes are visible. Once each week, have students move the Earth to its
proper position in relation to the sun.