Is there a difference in the duration of the seasons? That is what you are going to find out. Let's lump spring and summer together and call them the warm season. We will do that as well for fall and winter and call it the cold season.
You should already know when each of these two seasons start (astronomically). For uniformity in our numbers, let's consider the date of the beginning/end of the warm season for the year 2014. You will also need to know the date for the end of the cold season in 2015.
Beginning of warm season (2014) = ___March 20______
End of warm season (2014) = __September 23___ (this also is the beginning date of the cold season)
End of cold season (2015) = ____March 20_______
Do your calculations to determine how many days each season lasts.
Warm season (2014) lasts __187___ days
Cold season (2014-2015) lasts __178_ days (the two should total 365 days as a check)
This is worth 5 points. For the remaining 15 points, offer a logical astronomical reason why this is so.
Your first impression might be that it has something to do with our tilt. Amazingly, the degree of tilt has nothing to do with why there are so many more "warm season" days in a year. About all the tilt does here is help define when each season starts ... not how long they last. The answer all boils down to Kepler's laws. You know that the earth travels in an elliptical path around the sun. Let's exaggerate the degree of eccentricity here to illustrate the point. The image below shows the approximate position of the earth at the start of the warm and cold seasons. As you can see, the earth travels a greater distance (shown in red) during the warm season. That alone will make the warm season last longer. In addition to that, we know that the earth travels slower during the warm season (since we are further from the sun). This, too, will cause the duration of the warm season to increase. I'm happy if you can discover either of these two explanations. Finally, there is another way you can explain the answer. The actual duration of each individual day varies in each of these seasons. When we are close to the sun, each individual day is actually longer in duration which we learn in this unit as a solar day (so that affects how many days you can squeeze in during the cold season). The opposite is true during the warm season. Most students don't explain it this way.