In the Northern hemisphere, the shortest day and longest night of the year falls on December 21. Solstice means "standing-still-sun." Winter solstice occurs when, because of the earth's tilt, our hemisphere is leaning farthest away from the sun; therefore, the daylight is the shortest and the sun has its lowest arc in the sky.
Since ancient times people have kept track of the length of days so they could understand where they were in the year. On the shortest day they knew that winter was halfway over. Understanding the time of year was very important to ancient farmers, just as it is to farmers today. Seeds needed to be planted at the right time. Crops from seed sown too early would be destroyed by bad weather. Crops planted too late would not have time to mature for harvest.
Today Oklahoma farmers have very sophisticated tools for tracking length of days, soil temperature and moisture, rainfall and many other factors to help determine exactly the best time to plant, fertilize, etc. Oklahoma Mesonet provides volumes of useful information to Oklahoma farmers on its AgWeather site.
Lead a discussion about the length of days. Have students noticed there are activities they are no longer able to do in the evenings? Have they noticed it is darker outside when they wait for the bus in the morning?
- Keep a journal for the month of December showing how the length of days affects your activities.
- Pretend you are an ancient farmer on the shortest day of the year. What are your thoughts?