Yesterday was my sister’s anniversary, and that made me think about how many rituals and celebrations are based on one rotation of the earth around the sun: Birthdays, anniversaries, holidays, school years, mating seasons, and harvests… All these are based on our orbital geography around our galaxy’s star.

Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi),[1] and one complete orbit takes 365.256 days (1 sidereal year), during which time Earth has traveled 940 million km (584 million mi). ~ Wikipedia

We celebrate events based on yearly journeys of 940 million kilometres. That works out to over 2.5 million kilometres a day! Would this yearly trip have been as significant if the earth’s axis was not tilted, giving rise to the changing seasons?

Perhaps one of the most apparent factors contributing to Earth climate change is the angle at which the earth is tilted. This is the angle at which Earth’s axis of rotation is from the vertical, also known as Earth’s obliquity. Earth’s current tilt angle is approximately 23.5 degrees. The axial tilt angle affects climate largely by determining which parts of the earth get more sunlight during different stages of the year. This is the primary cause for the different seasons Earth experiences throughout the year, as well as the intensity of the seasons for higher latitudes. For example, in the Northern Hemisphere, if there were no axial tilt, i.e. Earth’s obliquity would be zero degrees, then there would be no change in the seasons from year to year. This would be because there would be no difference in the amount of solar irradiation received, year-round, anywhere on Earth. ~ Wikipedia

What would life be like if temperatures stayed relatively constant depending on your latitude? How important would birthdays be? Would our calendars be based on the moon? How important would the passing of a year be?

Enjoy your next orbit!