On Monday, March 20, we celebrate the spring equinox, scientifically known (in the Northern Hemisphere) as the vernal equinox. The equinox marks the moment the Sun crosses the celestial equator – the imaginary line in the sky separating the Northern and Southern Hemispheres.
Since the Earth orbits the sun at a tilt, each hemisphere receives the majority of the sunlight for half of the year. However, there is a point, twice each year, when the tilt of the Earth’s axis and Earth’s orbit combine in such a way that the sun is directly over the equator. For a moment both hemispheres receive equal sunlight, and night and day are approximately equal in length. The word equinox comes from the Latin aequus (equal) and nox (night).
During the vernal equinox, the Sun crosses into the North, and we celebrate the first day of astronomical spring. For the next six months, the sun's rays will be more direct for us than for those below the equator. The arc of the sun will shift north as it travels across the sky each day. In response to this shift, plants bud, birds and butterflies migrate north, and we experience longer days. Southern Hemisphere residents experience the astronomical opposite—the autumnal equinox—as the Sun heads away from them.
All Hail Spring
Since the equinox is synonymous with spring, it has been celebrated since ancient times, although differently in different cultures:
- In Christian cultures, spring brings Easter, the rebirth of Christ. Eggs, symbolizing fertility and rebirth, are symbols of both Easter and spring. Traditions such as egg rolls, egg hunts and egg decorating are enjoyed around the world.
- Ancient China gives us the vernal equinox tradition of balancing eggs on one end, to bring luck and prosperity.
- In Iran, the vernal equinox brings in the New Year, in accordance with the Persian astronomical calendar. Called No-Ruz, it has been celebrated for over 3000 years. The celebrations, which include cleaning house and buying new clothes, last for about 12 days.
- In Japan, both spring and fall equinoxes are a time to honor one’s ancestors. The spring celebration is called Higan, which means "other shore," a reference to spirits reaching Nirvana after crossing the River of Existence.
Here are some fun hands-on activity ideas to do in your classroom:
- Decorate eggs!
- Plant spring flowers. Each student can plant their own seed in a small pot, marked with their name, and care for it until it sprouts. When all have sprouted, lead an outdoor hike to a nearby field, where the students can plant their seedlings with room enough to grow and spread.
- Celebrate spring foods by researching (individually or as a class) traditional spring and Easter foods in different countries. Cap it off with a snack of hot cross buns or devilled eggs with alfalfa sprouts.
- Tell the legend of the Phoenix, an ancient symbol of the Sun, rebirth, and resurrection.
- Use the concept of kinesthetic astronomy to help students understand the orbit and rotation of the Earth. The students use their bodies to represent the objects and movements in the solar system, rotating and orbiting at the same time around a basketball "sun." Click here for more specifics.
Spring’s concept of renewal is a great time for you and your students to reevaluate your progress for the year, and reenergize yourself for achieving your goals. It’s also a great time to get outdoors and celebrate Nature!
What are your ideas for bringing the equinox to life in your classroom?
If you have a story or tip, please share in the comments!