Axial Tilt: the reason for the season!
As we circle the sun on our cozy spaceship Earth, we are lucky enough to do so at an angle. 23.5 degrees, to be specific.
Katie pondering axial tilt. Photo: Carolina Guererro 2021
There are many reasons that the time around the winter solstice became a popular one for holding loved ones close and celebrating birth and rebirth. I grew up celebrating Christmas with my family and participating in friends' Hannukah celebrations. The seven principles of Kwanzaa have become very important to me in my community. The principles of unity, self-determination, collective work and responsibility, cooperative economics, purpose, creativity, and faith drive my purpose for starting a business that helps solve big problems. On New Year’s Eve or Day, my husband Steve and I take a few moments to reflect on what we loved from the past year and what we want to bring from the coming year.
I don’t have to tell you all that it’s been another rough one for so many of us. This makes me even more grateful that we find so many ways to celebrate at this time of year. It is no coincidence that our winter celebrations all bring elements of light into focus: the lighting of Kwanzaa candles, the menorah, Christmas tree lights and stars, the burned yule logs of Wiccan winter solstice celebrations, the sparklers and fireworks of New Year’s Eve. For those of us living in the Northern Hemisphere, these celebrations coincide with a return of the sun. The darkest day is over, and we begin witnessing the slight lengthening of days. The promise of spring returns.
Katie’s holiday greeting gif. So festive!
(c) GeoLiteracy, LLC 2021
For me, the bit of nostalgia I feel as the long summer days start slipping away is replaced by an appreciation for the amazing way the Earth supports life through seasons.
Without our 23.5-degree tilt, the Earth would not have seasons.
Where would that leave us? Would you experience March 20th or September 22nd year-round? Nope. You would not.
Even though the position of the Earth relative to the sun would be the same as it is on the spring solstice or the autumnal equinox, the beauty of Earth’s seasons is that they allow for cycles of warming and cooling. Cycles of birth, senescence, and rebirth. These cycles are baked into how all of our ecosystems function.
They underlie the soil cycle, allowing the most fertile temperate latitude agricultural land to produce our breadbasket crops.
Seasons give seasonality to our precipitation cycles, giving us the challenging but ecologically necessary wet summers or snowy winters that feed our rivers.
They give us spring flowers, fall leaf color (that turns into nutrient-rich soil), and support animal food webs that, in turn, support human life.
Without a tilt, the Earth could be uninhabitable cold, with polar weather dominating the globe. With a wider tilt, seasons could be more extreme, preventing the planet from stabilizing.
Super smart astrobiologists continue to explore space, seeking out other planets that could support life, and estimating what conditions might support such life elsewhere. A moderate axial tilt is one of the criteria they consider because it allows for temperature moderation.
Every December 21st, I save a moment of holiday awe and gratitude for the amazing conditions that make our planet home.
Wishing all of the best to you, your kin family, your friend family, and, especially your pets!
Here’s to more GeoLiteracy in 2022.
