Download Seasons and the Tilted Earth Name TEK 8.7A Date Period _____

Seasons and the Tilted Earth
TEK 8.7A
Name ____________________________
Date __________________ Period _____
Most places on Earth experience four seasons every year. These are spring, summer, fall
and winter. The seasons are caused by a combination of things:
 The Earth being tilted as it moves around the sun.
 Direct sunlight producing more heat than indirect light.
 The Earth moving around the sun in a non-circular way.
This is how it works. Remember that the Earth is tilted all the time that it is
moving around the Sun. The Earth moves around the Sun once every year. It follows an
elliptical orbit. This means that it goes almost in a circle around the sun, but gets a little
further away at some times. The path it takes is like an oval.
When the Northern hemisphere is pointing at the sun, sunlight falls most directly
on it. This is summer in the Northern Hemisphere because direct light causes more heat
than indirect. As the Earth moves around to the other side of the Sun the Northern
Hemisphere is tilted away from the Sun. Now the light falls indirectly on it. It is winter.
When the Northern Hemisphere has summer, the Southern Hemisphere has winter, and
the other way round.
The Earth's axis is tilted 23.45°. This tilting is what gives us the four seasons
of the year: Summer, spring, winter and fall. Since the axis is tilted, different parts of
the globe are pointed towards the Sun at different times of the year. Summer is warmer
than winter (in each hemisphere) because the Sun's rays hit the Earth at a more direct
angle during summer than during winter and also because the days are much longer than
the nights during the summer. During the winter, the Sun's rays hit the Earth at an
extreme angle, and the days are very short. These effects are due to the tilt of the
Earth's axis.
Adapted by KA Baker, Godley Middle School, 2012, from M. Poarch – 2001 http://science-class.net
Now you think the teacher is daft, because it seems like she has said the same thing
many times. I have and I hope you get it.
Before you begin lab:
1. What is the shape of the Earth’s orbit? ___________________________________
2. Does the Earth’s distance from the sun change very much during the year? _________
3. If the Earth did move closer or farther from the Sun, would it be colder or hotter
everywhere on Earth at the same time? ________ What evidence did you use to support
your answer?_________________________________________________________
Materials:
Styrofoam Earth model
light source
Procedure:
1. Label the color of the dots below to match the earth model.
Spin Axis
2. Hold your model with the spin axis in a vertical position. Slowly spin counterclockwise
the model and watch the dots go from daylight to night and back to daylight. When the
spin axis is vertical, do the dots stay in the light the same amount of time during
rotation? _______________________
3. Is this how the Sun-Earth system really works? Why or why not? _______________
__________________________________________________________________
__________________________________________________________________
Adapted by KA Baker, Godley Middle School, 2012, from M. Poarch – 2001 http://science-class.net
4. Tilt the Earth toward the sun, roughly halfway down. Spin the Earth model again and
observe the dots. Compare what is happening at the red dot (mid-latitude North) and the
black dot (mid-latitude South). ___________________________________________
__________________________________________________________________
__________________________________________________________________
5. What is happening to the blue dot? ______________________________________
__________________________________________________________________
__________________________________________________________________
6. What is happening at the South Pole? ____________________________________
__________________________________________________________________
__________________________________________________________________
7. Compare what is happening in the two Northern cities. _______________________
__________________________________________________________________
__________________________________________________________________
8. What season is it on the red dot? _______________________________________
9. What season is it on the blue dot? ______________________________________
10. How are they different? ____________________________________________
__________________________________________________________________
11. All of the Northern hemispheres in our models are tilted toward the Sun, and have
summer. Is this how it really is? _____________Explain _______________________
__________________________________________________________________
__________________________________________________________________
Adapted by KA Baker, Godley Middle School, 2012, from M. Poarch – 2001 http://science-class.net
12. How does the season change from summer to fall to winter to spring and back to
summer during the year?________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
13. As the Earth moves around the Sun, the North Pole always points toward the North
Star. Point your model toward the “North Star.”
North Star
14. Label each hemisphere with the appropriate season.
Adapted by KA Baker, Godley Middle School, 2012, from M. Poarch – 2001 http://science-class.net