Understanding the Spring Equinox: An Astronomical Glimpse at the Start of Spring 2025
As we eagerly anticipate the arrival of spring and the end of the long, chilly winter days, one question looms in our minds: when is the first day of spring? In 2025, the spring or vernal equinox will occur at 5:01 a.m. EST on a Thursday, marking the official start of the spring season. But what does this mean, and why does it matter?
Simply put, an equinox is a celestial event that happens twice a year when the Earth’s equator aligns with the center of the sun. This alignment results in nearly equal durations of daylight and darkness at all latitudes. In the Northern Hemisphere, the equinox that occurs in late March is referred to as the vernal or spring equinox, signifying the arrival of spring. Conversely, in the Southern Hemisphere, this equinox denotes the arrival of autumn.
Why does this happen? Throughout the year, the Earth’s tilt and its path around the sun cause the amount of daylight each hemisphere receives to vary. During equinoxes, however, the tilt of the Earth’s axis is perpendicular to the sun’s rays. This results in an approximately equal distribution of daylight and darkness globally – hence the term ‘equinox’, derived from Latin, meaning ‘equal night’.
As spring advances, the Northern Hemisphere begins to tilt towards the sun, leading to longer, warmer days. This movement culminates in the summer solstice, the longest day of the year, which in 2025 will occur on Friday, June 20 at 10:41 p.m. EST. Post the solstice, the days will gradually start to shorten until the next equinox in September.
Another significant event related to these changes in daylight is daylight saving time, a practice adopted by many regions to make the most of the increased daylight hours. In 2025, for millions of Americans, daylight saving time will begin on Sunday, March 9, when clocks will “spring” forward by an hour.
Yet, it’s not just our clocks and calendars that tell us spring has arrived. If you enjoy stargazing, the arrival of spring can be discerned from the night sky as well. The Spring Triangle, an asterism formed by three bright stars in different constellations, becomes clearly visible in the sky of the Northern Hemisphere. So, if you’re wondering whether spring has begun, just look up at the night sky!
The vernal equinox and its associated changes serve as powerful reminders of the Earth’s annual journey around the sun and the fascinating celestial mechanics at play. Whether you see it as a harbinger of longer nights and gloomy weather, or a promising beacon of nicer temperatures and more daylight, there’s no denying the wonders of astronomy and the changing seasons. So, as we approach the first day of spring in 2025, let’s embrace the equinox and all that it signifies.
Contributing: Janet Loehrke, USA TODAY
Greta Cross is a national trending reporter at USA TODAY. Follow her on X and Instagram @gretalcross. Story idea? Email her at gcross@usatoday.com