The seasons

AimTo show how the revolution of the

Earth around the Sun is the reason for seasons.

To explain this using a model of the Earth.

MaterialsThe model of the Earth you made in

“Day and Night”A polystyrene ballTextasA wooden skewerA light source

Method

1. See Day and Night for instructions on making the model of the “Earth”

2. Put a second star on the balloon to represent a friend in Northern hemisphere

3. Answer the questions

Questions1. Hold the skewer so that the Earth is

positioned vertically. Rotate your model of the Earth directly in front of your light source.

a) Why is the length of day the same for both people?

b) If the axis was vertical (rather than being on an angle), would the seasons still exist? Explain.

Questions - Day LengthNow hold the model so it is on an approximate 23O angle, with the top pointed away from the light source. Rotate your model of the Earth.

2. Why is the length of day now different for people living in the Northern Hemisphere and the Southern Hemisphere?

Observations:3 Where does the sun rise first?4 Where does the sun set first? 5 Who has the longest day?

Questions - Seasons

Continue to hold the model so it is on an approximate 23O angle, with the top pointed away from the light source. Rotate your model of the Earth.

Interpretations:6 With the axis on this angle, is it

summer or winter in Australia?7 Is there anywhere the sun doesn’t set?

Is there anywhere the sun doesn’t rise?

Questions - SeasonsSummer in the Northern Hemisphere looks like this.

Make a labeled diagram of the Earth showing summer in the Southern Hemisphere.

Extension – Light IntensityContinue to rotate your planet on an angle of 23O. with the top pointed away from the light source.

7 Will the strength of the sun be the same for both you in the Southern Hemisphere and your friend in the Northern Hemisphere? Explain your answer.

8 What unit is used to measure light intensity and who used it first?

Extension – Imagine

9 The Earth spins on its axis at an angle of approximately 23 degrees to its orbit. Neptune spins at 90 degrees to its orbit. Long ago it was hit by a massive object resulting in its current orientation. Write a short story about a journey around Neptune.