Even if the leaves haven’t yet begun turning where you live, Labor Day is over, school is back in session and fall is almost here. The official arrival of the season is the autumnal equinox, which occurs in the Northern Hemisphere this month. 

After a hot summer, the September equinox marks a welcome shift in the seasons for many folks. But what exactly is an equinox? It’s all about Earth and its relationship with the sun. Here’s how to understand, visualize and celebrate the autumnal equinox.

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When is the autumn equinox?

This year, the autumnal equinox in the Northern Hemisphere falls on Monday, Sept. 22. If you want to be extra specific and mark it on your calendar, mark it for 11:19 a.m. PT.

Dates can shift slightly for equinoxes depending on the year, but it’s always around this time in September. The next vernal equinox in the Northern Hemisphere takes place on March 20, 2026, and will mark the start of spring.

What is the autumn equinox?

The meaning of equinox is right there in the name: a combination of the Latin words for equal and night. 

«There are only two times of the year when the Earth’s axis is tilted neither toward nor away from the sun, resulting in a ‘nearly’ equal amount of daylight and darkness at all latitudes,» the National Weather Service said in an explainer about the seasons. 

The Earth spins on an axis (imagine a line running from pole to pole) and the planet sports a jaunty 23.5-degree tilt. The tilt is what gives us seasons. As the Earth orbits the sun, the tilt means some areas of the planet get more direct sunlight than others. That’s how it can be summer in the Northern Hemisphere (tilted toward the sun) and winter in the Southern Hemisphere (tilted away from the sun) at the same time. During the equinox, the sun shines straight at the equator and gives equal love to the two hemispheres.

Other planets that are also tilted on their axes of rotation also experience equinoxes. The time scales can be very different, however. An equinox on Saturn only comes around about every 15 Earth years. That means each season lasts for over seven years on Saturn. It’s even wilder on Neptune, which has seasons that last decades. We can be grateful for the relatively short seasons on our planet.

What does an equinox look like?

Wherever you are on Earth on the day of the equinox (and whether it’s a spring or fall equinox, depending on which hemisphere you live in), the sun will rise as close to east and set as close to west as possible, making it a foolproof compass. Go outside and watch the sunset and sunrise, and make a note of the landmarks in front of the sun. That way, you’ll always know what exactly is west and east.

The two annual equinoxes also feature the fastest sunrise and sunset of the year, with the sun taking just a few seconds to appear and disappear. That’s because this is the steepest angle at which the sun rises and sets during the year.

How is an equinox different from a solstice?

As with equinoxes, solstices are associated with Earth’s tilt, but instead of daylight and nighttime being even, the days and nights are at their extremes. The winter solstice is the shortest day of the year, while the summer solstice is the longest. This year, the winter solstice for the Northern Hemisphere falls on Sunday, Dec. 21.

What does the equinox look like from space?

Earth-watching satellites up in orbit have a unique view of the equinox. A NASA Earth Observatory video shows Earth from space and how the positioning of the sun’s light shifts with the changing of the seasons. It’s a great way to visualize what’s happening during our planet’s orbit around the sun. 

Celebrating the equinox

Equinoxes aren’t like eclipses or meteors. There isn’t a big wow moment when you see something spectacular. The fall equinox this year will look like any other day, but it’s a handy way to mark the changing of the astronomical seasons. You can go around and declare, «It’s officially the first day of autumn!» How you celebrate is up to you. Here’s a suggestion: Put on your favorite sweater, go for a scenic foliage drive and sip a pumpkin spice latte to welcome fall in style.

Can generative AI animate a decent movie? That question’s getting an early test. OpenAI and production studio Vertigo Films have announced a plan to create a feature-length adaptation of a 2023 short film made as a demonstration for OpenAI’s Dall-E image generator. 

The film, called Critterz, has a budget of less than $30 million, and producers hope to make the movie in about nine months — in time for the Cannes Film Festival next May, according to reporting by The Wall Street Journal.

The short film, also called Critterz, was a play on the nature documentary genre, with the strange creatures in the forest suddenly showing they could understand and talk with the narrator. It was written and directed by Chad Nelson, now a creative specialist at OpenAI. Nelson used Dall-E to generate the images of the environment and the characters, tapping into traditional animation technique to bring the film to life. 

(Disclosure: Ziff Davis, CNET’s parent company, in April filed a lawsuit against OpenAI, alleging it infringed Ziff Davis copyrights in training and operating its AI systems.)

Vertigo Films said the full movie will be a family adventure that will «expand the world of the so-called Critterz characters.» James Lamont and Jon Foster, two of the writers behind the movie Paddington in Peru, will write the script. The Wall Street Journal reported that the film’s production team plans to feed sketches from human artists hired for the project into AI tools to animate them. Nelson said on LinkedIn that the film would use the latest research models from OpenAI «to innovate new production workflows.»

Read more: AI Essentials: 29 Ways You Can Make Gen AI Work for You, According to Our Experts

Image and video generators have come a long way just in the two years since the short film was made. Dall-E was impressive, but early image generators had notorious quirks, like giving people irregular numbers of fingers. Today’s tools can render much more realistic-looking images and video. While they aren’t perfect, tools like Google’s Veo 3 are good enough that AI-created slop is overrunning social media feeds, and it’s getting increasingly difficult to tell what video is real and what’s fake. 

The bigger question isn’t whether these tools can generate a film but rather whether they should — and whether audiences will want to see it. The use of generative AI is controversial in the film industry and in creative fields more generally. There’s also the issue of copyright, with OpenAI and other AI companies facing lawsuits from entertainment and media companies over the materials used to train their tools and the ability of some tools to generate things that look an awful lot like copyrighted characters. 

British telecoms company Vodafone is testing out a new spokesperson who appears as a woman in a red hoodie who speaks German and touts the benefits of high-speed home internet services.

One important note about this influencer: She’s AI-generated.

The character appears in a TikTok video posted three times on Vodafone’s official account, which has received more than two million views collectively. According to The Verge, the video has also appeared as an advertisement on X. In response to comments on the videos, the company said the AI spokesperson was part of various advertising tests it’s conducting.

In one response from the company’s social media team, translated from German, Vodafone said: «We’re trying out different styles. AI is so much a part of everyday life now that we’re trying it out in advertising too.»

A spokesperson (AI or otherwise) for Vodafone did not immediately return an email about the AI advertising.

Just last month, transportation company ScotRail reversed a decision to use an AI-generated voice on its trains after complaints.