Introduction to the Autumnal Equinox
While many people mourn summer with the passing of Labor Day Weekend, the autumnal equinox is the official end of the summer season.
Besides sweater weather and pumpkin-spiced menu items, what does the equinox mean, and when is it in 2025?
What is the Autumnal Equinox?
The autumnal equinox marks the start of autumn in the Northern Hemisphere.
The Earth travels around the sun at an angle, and for most of the year, the Earth’s axis is tilted either toward or away from the sun. That means the sun’s warmth and light fall unequally on the northern and southern halves of the planet.
When the Northern Hemisphere is tilted toward the sun, that’s called the summer solstice. This marks the first day of summer in the North and the first day of winter in the South. 180 days later, when the Southern Hemisphere is tilted toward the sun, it is called the winter solstice. This marks the first day of winter in the North and the first day of summer in the South.
The halfway points between these solstices are the autumnal and vernal equinoxes. The word equinox comes from two Latin words meaning equal and night. That’s because on the equinox, day and night last almost the same amount of time — though one may get a few extra minutes, depending on where you are on the planet. This provides approximately 12 hours of day, followed by 12 hours of night.
This year, there’s a bonus for some: Antarctica, New Zealand and a sliver of Australia may be able to see a partial lunar eclipse during their Monday.
When is the 2025 Autumnal Equinox?
This year, the autumnal equinox in the Northern Hemisphere — which can land between Sept. 21 and 24 depending on the year — will occur on Monday, Sept. 22 at 2:19 p.m. EST / 11:19 a.m. PT.
What’s the Difference Between Meteorological and Astronomical Season?
These are two different ways to carve up the year.
While astronomical seasons depend on how the Earth moves around the sun, meteorological seasons are defined by the weather. Meteorologists break down the year into three-month seasons based on annual temperature cycles. By that calendar, spring starts on March 1, summer on June 1, fall on Sept. 1 and winter on Dec. 1.
When is the "Harvest Moon" this Year?
The "Harvest Moon," which refers to the full moon that occurs closest to the autumnal equinox, is still a ways away. The name dates back to a time before electricity when farmers depended on the moon’s light to harvest their crops late into the evening, according to NASA.
This year, due to the lunar cycle, the harvest moon falls on Oct. 6. While it is visually no different than any other full moon, the fall moon has inspired songs, poems and stories throughout history.
Mark your calendar because the seasons are changing! Here’s what you need to know about equinoxes and solstices.
Conclusion
The autumnal equinox is a significant event that marks the beginning of autumn in the Northern Hemisphere. It is a time of change, when the days and nights become equal in length, and the weather starts to cool down. Whether you follow the astronomical or meteorological seasons, the autumnal equinox is a great opportunity to appreciate the beauty of nature and the changing seasons.
FAQs
- Q: What is the autumnal equinox?
A: The autumnal equinox marks the start of autumn in the Northern Hemisphere, occurring when the Earth’s axis is tilted neither towards nor away from the sun, resulting in equal day and night lengths. - Q: When is the 2025 autumnal equinox?
A: The 2025 autumnal equinox will occur on Monday, Sept. 22 at 2:19 p.m. EST / 11:19 a.m. PT. - Q: What is the difference between astronomical and meteorological seasons?
A: Astronomical seasons are based on the Earth’s movement around the sun, while meteorological seasons are defined by the weather and temperature cycles. - Q: When is the "Harvest Moon" in 2025?
A: The "Harvest Moon" in 2025 will occur on Oct. 6.
