Summer isn’t technically over yet, but fall is almost here. There are certain times when the seasons of the stars officially turn — in the fall, it’s the autumnal equinox. For spring, the vernal equinox.
The autumnal equinox in the Northern Hemisphere is in September, and it marks a welcome change in the seasons for many after a long, hot summer. But what exactly is the equinox? It’s all about the Earth and its relationship with the sun. Here’s how to understand, visualize and celebrate the autumnal equinox.
What is the autumnal equinox?
The meaning of equinox is there in the name: a combination of Latin words equal to night.
“There are only two times of the year when the Earth’s axis is not tilted or away from the sun, resulting in ‘nearly’ equal amounts of light and dark everywhere,” the National Weather Service explains about sunlight. the seasons.
A NASA image shows the angle of the Earth’s tilt relative to the Sun.
The Earth rotates on its axis (think of a line from pole to pole) and the planet is tilted at 23.5 degrees. The tilt is what gives us the seasons. As the Earth revolves around the sun, the tilt means that some areas of the planet receive more direct sunlight than others. That is how summer in the Northern Hemisphere (tilted towards the sun) and winter in the Southern Hemisphere (tilted away from the sun) are at the same time. During the equinox, the sun shines directly on the equator and gives equal love to the two hemispheres.
Other planets that are also tilted on their axis of rotation also experience the equinox. Timescales can vary greatly, however. The equinox on Saturn comes only about every 15 Earth years. That means each season lasts more than seven years on Saturn. It’s especially difficult for Neptune, whose seasons last for decades. We can be thankful for the relatively short seasons in our world.
When is the autumnal equinox?
The autumnal equinox in the Northern Hemisphere falls on September 22 this year. If you want to be more specific and put it on your calendar, then mark it at 5:44 am PT.
The dates for the equinoxes can change slightly depending on the year, but they are always around this time in September. The next vernal equinox in the Northern Hemisphere occurs on March 20, 2025, and will mark the beginning of spring.
What does the September equinox look like?
Wherever you are on Earth on the day of the equinox (and whether it’s the spring or autumn equinox, depending on which hemisphere you live in), the sun will rise as close to the east and stay as close to the west as possible, making the compass useless. Go outside and watch the sunset and sunrise, and note the landmarks in front of the sun — that way, you’ll always know what is west and east.
The two equinoxes of the year also mark the fastest sunrise and sunset of the year, with the sun taking only a few seconds to appear and disappear. This is because this is the steepest angle at which the sun rises and sets during the year.
How is the equinox different from the solstice?
This National Weather Service image shows the tilt of the earth, how it revolves around the sun and when the equinoxes and solstices occur in the northern hemisphere.
Like the equinoxes, the solstices are associated with the tilt of the Earth, but instead of the days and nights being equal, the days and nights are at their highest. Winter solstice is the shortest day of the year, and summer solstice is the longest. The Northern Hemisphere’s Winter Solstice occurs on Dec. 21 this year.
See the equinoxes from space
Earth-observing satellites in high orbit have a unique view of the equinox. A NASA Earth Observatory video shows Earth from space and how the position of sunlight changes with the changing seasons. It’s a great way to visualize what happens during our planet’s orbit around the sun.
How to celebrate the autumnal equinox
Autumn means it’s autumn sightseeing time.
Equinoxes are not the same as solar eclipses or meteors. There is no great moment when you see something amazing. This year’s autumnal equinox will look like any other day, but it’s a useful way to mark the changing seasons in the stars. You can go around and announce, “It’s officially the first day of fall!” How you celebrate is up to you. Here’s a suggestion: Put on your favorite sweater, go for a drive through the beautiful foliage and sip a pumpkin spice latte to welcome fall in style.