The first day of spring is widely associated with a spirit of rejuvenation. But flowering plants and warming temperatures are not the only reasons to celebrate the arrival of the spring equinox. According to the National Weather Service, the spring equinox, together with the autumnal equinox, is one of only two times of the year when Earth’s axis is tilted neither toward nor away from the sun. This results in a near-equal amount of daylight and darkness at all latitudes. The NWS notes that the nearly equal hours of day and night results from a refraction of sunlight, or a bending of the light’s rays that causes the sun to appear above the horizon, even though its actual position is below the horizon. In 2020, the spring equinox in the northern hemisphere occurs on March 19. While it’s easy to embrace the arrival of spring as a mere harbinger of warmer weather to come, the first day of spring also is a great time to pause and reflect on just how unique the equinoxes are.