**The Astronomical Start of Spring Arrives, Marking the End of Winter** On Friday, March 20, the vernal equinox occurred at 10:46 a.m. ET/7:46 a.m. PT, signaling the official start of spring in the Northern Hemisphere. This marked the tipping point into longer days, as the Northern Hemisphere transitions from being pointed away from the sun to being pointed toward it. The spring equinox is a significant astronomical event that marks the shift in seasons, and it is essential to understand what it is and why it happens. The word "equinox" originates from the Latin words for equal and night, as daylight and night are roughly equal during this time. The vernal equinox marks the beginning of longer days, while the autumnal equinox marks the beginning of shorter days. The Earth's tilt, which is approximately 23.5 degrees, is responsible for the changing seasons. "The spring equinox is when the Northern Hemisphere transitions from being pointed away from the sun (during winter) to being pointed toward the sun (during summer)," explained Emily Rice, associate professor of astrophysics at the Macaulay Honors College of the City University of New York. The Earth's orbit and tilt are closely aligned during the equinox, resulting in nearly equal amounts of daylight and night. This is in contrast to solstices, which are the extremes of days and nights. The summer solstice, which occurs on June 21 in the Northern Hemisphere, is the longest day, while the winter solstice, which occurs on December 21, is the shortest. Solstices receive more attention than equinoxes, as they are easier to mark and visualize. "The extremes are easier to mark and to visualize than the inflection points, which are more subtle changes, so the solstices get all the attention," said Rice. To visualize the Earth's tilt and the equinox, NASA has created a video showing the planet's orbit and the shifting of night and daylight. The video provides a unique perspective on the equinox and the changing seasons. While the spring equinox may not be as well-known as the solstices, it is an essential event that marks the beginning of longer days and the end of winter.