Winter Solstice - December 21

The four seasons add special spice to our lives. We celebrate each change by performing seasonal tasks and rituals--planting gardens and crops in the spring, swimming and hiking in the summer, raking mountains of fall leaves, and shoveling snow and drinking cups of hot cocoa on a winter day. Granted, tasks and rituals will differ depending on where you live in our country. And we owe it (almost) all to the fact that the Earth's axis is tilted 23 1/2 degrees.

Because of the tilt, as the Earth makes its yearly orbit around the sun, different parts of the Earth get different amounts of sunlight. December 21 or 22 is the day of the year that the Northern Hemisphere gets the fewest hours of sunlight. This shortest day--and longest night--is the winter solstice.

Connections

This subject lends itself beautifully to using models to help students see why we have seasons. A number of variations on the big ball (sun), small ball (Earth), flashlight (sunlight) model are offered in the resources below.

The winter solstice provides a great opportunity for students to learn and practice map skills. Involve the students in making diagrams of the Earth showing important lines of latitude and indicating the sun's relationship to each of these lines at different seasons.

In a link with social studies, older students can explore how the solstice is celebrated in different countries and cultures. For example, in China the winter solstice is called Dongzhi and is celebrated with feasts. In Iran, the solstice is known as Yalda, and families celebrate by eating fruits and nuts and burning bonfires.

For a language arts connection, read Jane Yolen's Ring of Earth, a poetry book for all seasons. You might want to divide the class into "seasonal groups," assigning each group the poems that represent its season. Students can share these poems aloud. This sharing is an excellent prewriting activity for the students' own poems.

Web Resources

• Fundamentals of Physical Geography - This site explores how the Earth's tilt, rotation, and revolution create the seasons. Good background information for teachers, with graphics and tables available.
• The Distant Sun - This NASA article covers some of the same information as the resource above but is a little easier to read. It also adds some very interesting information-it explains how differences in the ability of land and water to hold heat influences temperatures on Earth and why summer is a few days longer in the Northern Hemisphere than in the Southern Hemisphere. The information in the article is presented at a suitable reading level for older students, and there is a link to an audio version in case you would like your students to listen to it.
• Earth's Seasons: Equinoxes, Solstices, Perihelion, and Aphelion, 1992-2020 - Published by the U.S. Naval Observatory, this table presents the times of the solstices and equinoxes, down to the exact minute and second, for 1992 to 2020.
• A Sunwheel for the Campus - This site explains what a sunwheel is-a solar calendar and an observatory-and describes and documents the construction of a sunwheel at the University of Massachusetts.
• Ask a High Energy Astronomer - In a question and answer format, this site explains the seasons in terms of average daytime temperature and hours of sunlight.
• Seasons of the Year - This site offers a good explanation, with diagrams, of the solstices and equinoxes. It also notes the effects of oceans and discusses the Earth's distance from the sun. There is an interesting link to a page on the brightest full moon of the last century (1999), which occurred during the winter solstice.
• Interplanetary Seasons - On this site, you'll find information about seasons on other planets and a comparison of Earth and Mars.
• Asteroids Have Seasons, Too - This site briefly describes seasons on the asteroid Eros, plus other interesting information on the asteroid.
• Chinese Festivals - Winter Solstice - Learn about celebrations of the winter solstice--Dongzhi--in China.
• Winter Solstice:Dongzhi - Read about a traditional Chinese activity that involves an unfinished picture of a plum tree. Every day, students fill in part of the picture with a symbol representing the weather for that day. By the time the students finish filling in the picture, spring has arrived.
• Yalda - Read a brief history of the winter solstice in ancient cultures such as Persia and how the solstice is celebrated there today.

Ready-to-Go Activities

• A Song for All Season - Grades K-8. This is a fun site! Students listen to excerpts from Vivaldi's "The Four Seasons." Then they must decide which season they are listening to and thus which hemisphere--if either--is tilting toward the sun.
• Astronomy with a Stick: Daytime Astronomy for Elementary and Middle School Students - Grades 3-8. This site provides activities to track the revolution and rotation of the Earth in relation to the sun.
• Reason for the Season - Grades 6-8, but can easily be adapted to lower grades. Here are some variations on the sun-Earth model to help students visualize why there are seasons.
• The Earth's Orbit - Grades 2-6, but could easily be incorporated into lessons for Grade 7 and 8. You will find numerous activities on this site related to the Earth's orbit, such as tracking the sun's path and measuring the Earth's tilt.
• Using Shadows to Find the Four Direction - Grades 6-9. A lesson plan for using shadows to find the four cardinal directions.
• Sun, Earth, Moon - Grades 8-12. This site has very nice animations and clearly written explanations of the Earth orbiting the sun, eclipses, and the phases of the moon.