December 21st is the shortest day in the northern hemisphere. It marks the first day of winter up here. Cosmically, agriculturally, and historically, there’s a lot to celebrate.
The Earth’s rotation and orientation to the sun give us our four seasons: winter, spring, summer and fall. Earth revolves around the sun once every 24 hours, creating day and night. Our planet orbits the sun in 365 days, which we call a year. The Earth is tilted on its axis at approximately 23.5°. This angle stays constant as the Earth orbits the sun.
The tilt of our little blue and green planet on its axis and the orientation of the axis to the sun creates all the seasonal variations that we Earthlings experience.
The winter solstice occurs around December 21st when the North Pole is facing away from the sun and the South Pole is facing the sun. Northern regions experience the shortest period of daylight on this day. This begins winter in the northern hemisphere.
Summer solstice occurs around June 21st when the northern hemisphere is tipped toward the sun. This day is the longest day. This begins summer in the northern hemisphere.

Cultures all over the world have historically celebrated the shortest day and the longest night. The word solstice comes from Latin. Sol means ‘sun’ and sistere means ‘stop’.
Scandinavian’s traditionally celebrate St. Lucia’s Day, a festival of lights marking the winter solstice. Today it is meant to honor St. Lucia, yet it incorporates Norse solstice traditions, such as lighting fires to ward off spirits during the longest night.
In China, families celebrate the year they’ve had with Dong Zhi, the “arrival of winter.” The holiday generally falls between the 21st and 23rd of December and is thought to have started as an end-of-harvest festival with workers returning from the fields and enjoying the fruits of their labors with family.
The ancient Roman festival of Saturnalia is linked with the modern celebration of Christmas. In pre-Christian times, Romans celebrated the end of the planting season around the solstice with feasts and gift-giving.
In Iran, the festival Yalda, or Shab-e Yalda has celebrated the winter solstice since ancient times. It marks the last day of the Persian month of Azar. Yalda is viewed as the victory of light over dark and celebrates the birthday of the sun god Mithra.
Celebrate the solstice with your petite Earthlings with our Winter Solstice lesson plan.