1. Seasons Understand how seasons work on the Earth
Literal world building of other planets
Examples:
Indigenous religions, local calendars
Weather, planting seasons
Bad example: “Winter is coming.”

2. Why you should care about wrong ideas
Your preconceptions can cause inaccuracies in your writing
Readers’ misconceptions can cause confusion when reading
To accurately communicate, you need to know both the correct science and what your readers think

3. Answer the following questions privately to me using the colored cards

4. What season is it right now in Australia?
Spring
Summer
Fall
Winter

5. What causes the seasons on Earth?
Earth’s elliptical orbit causes it to sometimes be closer to the Sun
The tilt of the Earth’s axis causes more direct rays from the Sun
The tilt of the Earth’s axis causes parts of the Earth to be closer to the Sun
The tilt of the Earth’s axis changes so parts of the Earth are closer to the Sun

6. Popular Answer: A
The Earth’s orbit is elliptical. Seasons are caused by the entire Earth’s distance from the Sun.

7. A Private Universe
Harvard Smithsonian Center for Astrophysics (CfA), 1987
Start 0:25
End first segment 3:16
5:00

8. A Private Universe
Harvard Smithsonian Center for Astrophysics (CfA), 1987
0:35-2:15
End first segment 3:16
5:00

9. Popular Answer: A
The Earth’s orbit is elliptical. Seasons are caused by the entire Earth’s distance from the Sun.

10. Problems with A
Whole Earth would experience the same seasons at the same time
How does this explain the length of the day?
Why doesn’t the Sun look bigger in the Summer than the Winter?

12. What causes the seasons on Earth?
Earth’s elliptical orbit causes it to sometimes be closer to the Sun
The tilt of the Earth’s axis causes more direct rays from the Sun
The tilt of the Earth’s axis causes parts of the Earth to be closer to the Sun
The tilt of the Earth’s axis changes so parts of the Earth are closer to the Sun

13. 23.5º Tilt of Earth’s axis

14. 2nd most Popular Answer: C
Tilt of the Earth makes part of the Earth closer to the Sun and therefore warmer.

15. Problem with C
Which part of the Earth is closer to the Sun?
Equator

17. 23.5º Tilt of Earth’s axis alone
Nothing to do with distance
Directness of sunlight
Length of day
Path of Sun through the sky

18. Demos Seasons: Rise/set of stars
Rise/set of stars
“The Stars: A New Way to See Them” (by H.A. Rey)

19. What causes the seasons on Earth?
Earth’s elliptical orbit causes it to sometimes be closer to the Sun
The tilt of the Earth’s axis causes more direct rays from the Sun
The tilt of the Earth’s axis causes parts of the Earth to be closer to the Sun
The tilt of the Earth’s axis changes so parts of the Earth are closer to the Sun

20. Imagine that the Earth was upright with no tilt
Imagine that the Earth was upright with no tilt. How would this affect the seasons?
We would no longer experience a difference between the seasons.
We would still experience seasons, but the difference would be less noticeable.
We would still experience seasons, but the difference would be more noticeable.
We would continue to experience seasons in essentially the same way as we do now.

21. Bad Example: “Winter is coming.”
In A Song of Ice and Fire (book series) and A Game of Thrones (TV series), Martin says Bran is 7 years old, and that he has not yet experienced winter.
Huh? Martin doesn’t explain how years can be independent of seasons.

22. Possible Explanations of “Winter is coming.”
Variable tilt?
Not likely due to stabilizing effect of having a moon
Elliptical orbit?
Not likely due to variable winter length and decoupled year/seasons
Circumbinary planet?
El Nino / Southern Oscillation?