Autumnal Equinox in September Approaches: Essential Information and Expected Appearance
The autumnal equinox, a remarkable event in Earth's annual cycle, is approaching on Monday, Sept. 22, 2025, at 11:19 a.m. Pacific Time. This transition marks the beginning of fall in the Northern Hemisphere, signalling a shift from the hot summer months.
The term "equinox" derives from the Latin words for equal and night, indicating the approximate equal daylight and darkness at all latitudes during this period. The Earth's axis is tilted neither towards nor away from the sun, which is a key factor in the equinoxes.
On the day of the equinox, the sun rises as close to east and sets as close to west as possible. This steepest angle at which the sun rises and sets during the year results in the sun taking just a few seconds to appear and disappear.
The autumnal equinox is not accompanied by a spectacle like an eclipse or meteor shower, but it serves as a useful marker for the changing of the astronomical seasons. Many people welcome this change, viewing it as an opportunity to wear a favourite sweater, go for a scenic foliage drive, or enjoy a pumpkin spice latte.
Earth-watching satellites in orbit offer a unique view of the equinox, showing the shifting position of the sun's light as the seasons change. The autumnal equinox is a significant event in the Earth's relationship with the sun.
The winter solstice for the Northern Hemisphere in 2025 will occur on Sunday, Dec. 21. Conversely, the next vernal equinox (marking the start of spring) will take place on March 20, 2026. The winter solstice is the shortest day of the year, while the summer solstice is the longest.
The tilt of the Earth's axis causes seasons, with some areas receiving more direct sunlight than others as the Earth orbits the sun. This tilt also means that other planets with an equatorial tilt experience equinoxes, although the time scales can vary significantly. For example, equinoxes on Saturn occur approximately every 15 Earth years, and seasons on Neptune last for decades.
The equinoxes can help determine directions (east and west) by observing the sun's position during sunrise and sunset. During the equinox, the sun shines directly at the equator, giving equal light to both hemispheres.
In conclusion, the autumnal equinox is a fascinating event in Earth's journey around the sun. It serves as a reminder of the predictable and intricate dance between our planet and its star, providing a useful marker for the changing of the seasons. So, as we approach the autumnal equinox in 2025, take a moment to appreciate this natural wonder and enjoy the start of a new season.
