The Reason for the Seasons: A Solution

Now that you’ve had a while to puzzle over our last mystery, let’s discuss the solution.

How can you improve your beliefs about the reason for the seasons? Of course, you could go look up the answer somewhere, but science is way more fun than books so we will use science instead. Also, while the reason for the seasons has a well known answer that is recorded in many books, most mysteries do not. So, let’s practice on this one for now and pretend that the answer isn’t in the back of the book.

Let’s suppose that you believe the seasons are caused by the Earth getting closer to and farther from the sun. This is a perfectly good belief for most people. It does seem to explain seasonal variation in the temperature. Also, it agrees with what we know about planetary orbits: Some planets are on anelliptical orbit around the sun, and get closer to and farther from the sun at different times of their year. That’s actually true!

So, this belief is perfectly useful. But, as scientists, we value being skeptical, even when a belief is perfectly good and useful. Skepticism is the first step from going from a belief that is just ‘good enough’ to better and better beliefs.

The first thing we should do is make a list of the consequences of our belief. Then, we should see if any of those consequences can be tested. If we design rigorous tests of each of the consequences and they all pass the test, then we know our belief is a good one. If it fails a test, we should try and think up a new belief that can pass that test as well as all the other ones.

Consequences of seasons caused by distance to the sun:

  1. Annual cycle of seasons.
  2. The whole Earth should experience the seasons at the same time.
  3. Summer when Earth is closest to sun, winter when Earth is farthest from the sun.
  4. Earth is on elliptical orbit with differences in distance large enough to account for the temperature differences.

The first one checks out. We do experience an annual cycle of seasons. In fact, that’s what our belief was designed to explain. Its only a little bit exciting when you can explain a phenomenon. What should really be exciting, though, is when the consequences of that explanation are actually realized in nature!

The second consequence is not part of our everyday experience because we only live in one Hemisphere of Earth for most of our lives. Often, our travels to other locations are much shorter than the length of a season, so we do not notice how the seasonal variations in other places are different. But, if we go outside our everyday experience and ask someone from the other side (north vs. south) of the world, we would discover that the seasons are backwards! The southern winter happens during the northern summer and viceversa.

The other two consequences also fail, but your probably can’t measure them on your own unless you are an astronomer.

This discussion is meant, of course, to be illustrative. We can get stuck believing something that’s ‘good enough’ for our everyday lives–even if it is untrue. People believed the Earth was flat because it was a ‘good enough’ belief for every day life. These are silly examples, but don’t be fooled into thinking that all of your beliefs are good.

Exercise is about having good fitness, not just fitness that’s ‘good enough’ to get you through your average day. Similarly, education is about having good beliefs, not just ‘good enough’ beliefs.


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