As the world prepares to embrace the arrival of spring, Thursday, March 20, 2025, will mark a significant transition in the astronomical calendar: the vernal equinox. This event is set to occur at 5:01 a.m. EST, which is 2:01 a.m. Pacific Time, and 1:07 p.m. Muscat time, as reported by various scientific authorities including the National Weather Service and the Oman Society for Astronomy and Space.
The vernal equinox, a moment when the sun is directly above the equator, symbolizes not only the start of spring in the Northern Hemisphere but also the transition to autumn in the Southern Hemisphere. On this day, most places on Earth will experience nearly equal lengths of day and night—approximately 12 hours of each—due to the Earth's axial tilt of 23.5 degrees.
Ilana MacDonald, an astrophysicist with the University of Toronto's Dunlap Institute for Astronomy and Astrophysics, explains, "The reason why we have winter is because that’s when the Northern Hemisphere is pointed away from the sun, so we get less sunlight. Once we pass that threshold—when the days are longer than the nights—it signals warming and ushers in spring.”
On March 20, in Muscat, Oman, daylight will last 12 hours, 7 minutes, and 24 seconds—exactly when the sun rises at 6:11 a.m., reaches its zenith at 12:14 p.m., and sets at 6:18 p.m. In Toronto, residents can expect about 12 hours and 10 minutes of sunlight on this day, a slight difference due to geographical variations.
This phenomenon occurs twice each year, with the second instance taking place during the autumnal equinox. The spring equinox—often associated with new beginnings and growth—fosters significant cultural and agricultural practices, such as planting crops, as the ground begins to warm. Traditionally, humans have marked this time as a seasonal change, celebrating the renewal of life.
As the sun transitions from the southern hemisphere to the northern, the moment is noted not just for its scientific implications but also for a range of cultural rituals that honor the new season. Notably, this year is different from last when the equinox occurred on March 19, marking the earliest first day of spring in 128 years. "The spring equinox occurs when the sun crosses directly over the Earth's equator," as described by the National Research Council of Canada, emphasizing the universal nature of this astronomical event.
While many refer to the start of spring as commencing on March 1 based on meteorological definitions, March 20 marks the astrological beginning, signifying a dual perspective on the changing seasons. Meteorologists, like those at NOAA, emphasize that astronomical and meteorological seasons rely on differing frameworks to track climate and weather trends: astronomical based on the sun’s position and meteorological on temperature cycles.
The transition into spring signifies a time of contrasts. For instance, while the Northern Hemisphere welcomes more daylight and warmth, the Southern Hemisphere prepares for cooler days as they experience autumn. The daylight hours will gradually lengthen until the summer solstice on June 21, when the days reach their maximum length.
This alignment with nature's cycles also has practical implications for agriculture, particularly in regions affected by weather variability. As spring unfolds, farmers in Central Canada may face challenges with above-average precipitation that could delay planting, yet they benefit from a reduced risk of frost as the season progresses. MacDonald notes, “Once we pass that threshold, and the days are longer than the nights, that means things start to warm up.”
As we prepare to celebrate this equinox, it is also an opportune moment to reflect on the environmental changes influenced by our planet's rotation. The equinox is one of four key astronomical events—alongside the summer solstice, autumnal equinox, and winter solstice—that mark the transition of seasons.
With all the excitement surrounding spring’s arrival, individuals and communities alike engage in various festivities and rituals aimed at welcoming the new season. From planting gardens to joining communal celebrations, the vernal equinox serves as a reminder of the cyclical nature of life and the environmental transformations ushered in by the tilt of the Earth.
As we look toward the warmer days ahead, it should not be overlooked that understanding these astronomical events enhances our appreciation for the planet and our place within its ever-changing environment. The upcoming summer solstice, scheduled for June 21, signals the continuation of this journey through the seasons, showcasing the beautiful interplay between light and life across the globe.
