The Knowledge
Why can’t it always be summer? It’s all about the Earth’s tilt
Earth’s axial tilt causes the seasons. As Earth orbits the Sun, different hemispheres tilt toward or away, creating summer and winter depending on location.
Last Updated on March 13, 2026 by Daily News Staff
Stephanie Spera, University of Richmond
Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.
Why can’t it always be summer? – Amanda, age 5, Chile
With its long days just itching to be spent by water doing nothing, summer really can be an enchanting season. As Jenny Han wrote in the young adult novel “The Summer I Turned Pretty”: “Everything good, everything magical happens between the months of June and August.”
But all good things must come to an end, and summer cannot last forever. There’s both a simple reason and a more complicated one. The simple reason is that it can’t always be summer because the Earth is tilted. The more complicated answer requires some geometry.
I’m a professor of geography and the environment who has studied seasonal changes on the landscape. Here’s what seasons have to do with our planet’s position as it moves through the solar system.
This animation shows why the Earth has seasons.
Closeness to the Sun doesn’t explain seasons
First, you need to know that the Earth is a sphere – technically, an oblate spheroid. That means Earth has a round shape a little wider than it is tall.
Every year, Earth travels in its orbit to make one revolution around the Sun. The Earth’s orbit is an ellipse, which is more like an oval than a circle. So there are times when Earth is closer to the Sun and times when it’s farther away.
A lot of people assume this distance is why we have seasons. But these people would be wrong. In the United States, the Earth is 3 million miles closer to the Sun during winter than in the summer.
Spinning like a top
Now picture an imaginary line across Earth, right in the middle, at 0° latitude. This line is called the equator. If you drew it on a globe, the equator would pass through countries including Brazil, Kenya, Indonesia and Ecuador.
Everything north of the equator, including the United States, is considered the Northern Hemisphere, and everything south of the equator is the Southern Hemisphere.
Now think of the Earth’s axis as another imaginary line that runs vertically through the middle of the Earth, going from the North Pole to the South Pole.
As it orbits, or revolves, around the Sun, the Earth also rotates. That means it spins on its axis, like a top. The Earth takes one full year to revolve around the Sun and takes 24 hours, or one day, to do one full rotation on its axis.
This axis is why we have day and night; during the day, we’re facing the Sun, and at night, we’re facing away.
But the Earth’s axis does not go directly up and down. Instead, its axis is always tilted at 23.5 degrees in the exact same direction, toward the North Star.
The Earth’s axis is tilted due to a giant object – perhaps an ancient planet – smashing into it billions of years ago. And it’s this tilt that causes seasons.
It’s all about the tilt
So that means in June, the Northern Hemisphere is tilted toward the Sun. That tilt means more sunlight, more solar energy, longer days – all the things that make summer, well, summer.
At the same time, the Southern Hemisphere is tilted away from the Sun. So countries such as Australia, Chile and Argentina are experiencing winter then.
To say it another way: As the Earth moves around the Sun throughout the year, the parts of the Earth getting the most sunlight are always changing.
Fast-forward to December, and Earth is on the exact opposite side of its orbit as where it was in June. It’s the Southern Hemisphere’s turn to be tilted toward the Sun, which means its summer happens in December, January and February.
If Earth were not tilted at all, there would be no seasons. If it were tilted more than it is, there would be even more extreme seasons and drastic swings in temperature. Summers would be hotter and winters would be colder.
Defining summer
Talk to a meteorologist, climate scientist or author Jenny Han, and they’ll tell you that for those of us in the Northern Hemisphere, summer is June, July and August, the warmest months of the year.
But there’s another way to define summer. Talk to astronomers, and they’ll tell you the first day of summer is the summer solstice – the day of the year with the longest amount of daylight and shortest amount of darkness.
The summer solstice occurs every year sometime between June 20 and June 22. And every day after, until the winter solstice in December, the Northern Hemisphere receives a little less daylight.
Summer officially ends on the autumnal equinox, the fall day when everywhere on Earth has an equal amount of daylight and night. The autumnal equinox happens every year on either September 22 or 23.
But whether you view summer like Jenny Han or like an astronomer, one thing is certain: Either way, summer must come to an end. But the season and the magic it brings with it will be back before you know it.
Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.
And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.
Stephanie Spera, Assistant Professor of Geography and the Environment, University of Richmond
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Forgotten Genius Fridays
The Elevator That Made Skyscrapers Possible
In 1853, Elisha Otis revolutionized city life with a simple invention—the elevator safety brake—making skyscrapers and modern skylines possible.
In the mid-1800s, buildings were limited by one thing: stairs. Climbing more than a few flights was impractical, which meant cities could only grow outward, not upward. But that all changed in 1853 when a man named Elisha Otis introduced a revolutionary invention—the elevator safety brake.
Before Otis, elevators existed, but they were dangerously unreliable. A snapped rope could mean certain death. Otis solved this with a mechanical safety device that stopped the elevator from falling if the cable failed. To prove his invention worked, he staged a dramatic demonstration at the New York World’s Fair: he stood on a platform, ordered the rope cut, and… nothing happened. The brake caught the elevator. The crowd gasped. History shifted.
Otis founded the Otis Elevator Company, which still powers many of the world’s tallest buildings today. His invention didn’t just make elevators safe—it made the modern skyline possible. Skyscrapers, as we know them, owe their existence to that bold moment and a man who believed cities should grow up, not out.
Without Otis, we’d still be climbing stairs.
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🔗 Related Links:
Otis Elevator Company – Official History https://www.otis.com/en/us/about-us/history Elisha Otis Biography – Britannica https://www.britannica.com/biography/Elisha-Graves-Otis How Elevators Changed the World – Smithsonian Magazine https://www.smithsonianmag.com/innovation/how-elevators-changed-world-180976152/ Historic Elevator Safety Demo (Video Recreation) https://www.youtube.com/watch?v=QF3guY4TwK4 The Rise of the Skyscraper – PBS Learning Media https://www.pbslearningmedia.org/resource/amex27sci.socst.ush.skyscraper/the-rise-of-the-skyscraper/
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
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Forgotten Genius Fridays is a weekly collection of short videos and articles dedicated to inventors, innovators, scientists, and creators whose impact changed the world—but whose names were often left out of the textbooks.
From life-saving inventions and cultural breakthroughs to game-changing ideas buried by bias, our series digs up the truth behind the minds that mattered.
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News Brief
Earthquake Swarm Shakes Southern California Near Salton Sea
Earthquake Swarm: A swarm of earthquakes near California’s Salton Sea and Brawley area has prompted increased monitoring by seismologists as hundreds of tremors shake the region.
A swarm of earthquakes has been rattling Southern California near the Salton Sea, drawing attention from residents and seismologists across the region.
Salton Sea earthquake swarm?
The activity is centered near Brawley in Imperial County, an area known for frequent seismic movement due to its location within the Brawley Seismic Zone. According to the U.S. Geological Survey, hundreds of small earthquakes have been recorded over the past several days, with the strongest reaching a magnitude of approximately 4.7.
Residents throughout Imperial Valley, parts of Riverside County, and even portions of Arizona reported feeling shaking from several of the larger quakes. Minor incidents such as falling objects and brief power disruptions were also reported, though no major injuries or widespread structural damage have been confirmed at this time.
The region sits near the southern end of the San Andreas Fault and is considered one of California’s most geologically active areas. Scientists say earthquake swarms are relatively common near the Salton Sea because of the interaction between tectonic fault systems and geothermal activity beneath the surface.
While experts continue to monitor the situation closely, they emphasize that earthquake swarms do not necessarily indicate that a larger earthquake is imminent. However, officials encourage residents to review emergency preparedness plans, secure heavy furniture, and keep emergency supplies ready.
The Salton Sea region has experienced similar seismic swarms in the past, making it an important area of study for earthquake researchers and emergency management agencies.
For continued updates on this developing story and other regional news, visit STM Daily News.
Related External Links
- U.S. Geological Survey (USGS) – Earthquake Monitoring
- California Institute of Technology (Caltech)
- California Earthquake Preparedness Guide
- Ready.gov – Earthquake Safety Tips
- USGS – Salton Trough and Seismic Activity
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The Knowledge
Artemis II crew brought a human eye and storytelling vision to the photos they took on their mission
Artemis II crew: Artemis II’s astronaut photos show how human perspective and storytelling make space imagery feel authentic—especially in an era of AI-generated visuals.
Christye Sisson, Rochester Institute of Technology
In early April 2026, the Artemis II mission captivated me and millions of people watching from across the world. The crew’s courage, skill and infectious wonder served as tangible proof of human persistence and technological achievement, all against the mysterious backdrop of space.
People back on Earth got to witness the mission through remarkable photos of space captured by astronauts. Images created and shared by astronauts underscore how photography builds a powerful, authentic connection that goes beyond what technology alone can capture.
As a photographer and the director of the Rochester Institute of Technology’s School of Photographic Arts and Sciences, I am especially drawn to how these photographs have been at the center of the public’s collective experience of this mission.
In an era when image authenticity is often questioned and with the capabilities of autonomous, AI-driven imaging, NASA’s choice to train astronauts in photography has placed meaning over convenience and prioritized their human perspectives and creativity.
Capturing space from the crew’s perspective
Photography was not originally placed as a high priority in NASA’s Apollo era. The astronauts only took photographs if they had the chance and all their other tasks were complete.
Thanks largely in part to public response to those images from Apollo, including “Earthrise” and the “Blue Marble” being widely credited for helping catalyze the modern environmental movement, NASA shifted its approach to utilize photography to help capture the public’s imagination by training their astronauts in photographic practices.
The Artemis II mission’s photographs have helped cut through the increasing volume of artificially generated images circulating on social media. NASA’s social media releases of the crew’s photographs have garnered thousands of shares and comments.
This excitement could be explained by the novelty of photos from space, but these images also distinguish themselves as products of astronauts experiencing these sights and interpreting them through their photographs. These differences require an important distinction around where technology ends and humanity begins.
Human perspective versus AI tools
Photography has long integrated AI-powered software and data-driven tools in a variety of ways: to process raw images, fill in missing color information, drive precise focus and guide image editing, among others. These modern technological assists help human photographers realize their vision.
Artificial intelligence is also increasingly capable of operating machinery competently and autonomously, from cars to drones and cameras.
And AI can generate convincing, realistic images and videos from nothing more than a text prompt, using readily available tools.
Researchers train AI to mimic patterns informed by millions of sample images, and the algorithm can then either take or create a photograph based on what it predicts would be the most likely version of a successful, believable image.
Human-created photos are rooted in direct observation, intent and lived experience, while AI images – or choices made by AI-driven tools – are not. While both can produce compelling and believable visuals, the human photographs carry emotional power because the photographer is drawing from their experiences and perspective in that moment to tell an authentic story.
Artemis II photographs resonate, not only because they are historic, but because they reflect the deliberate choices and intent of a human being in that specific moment and context. The exposure, camera setting, lens choice and composition are all dictated by the astronaut’s vision, skill, perspective and experience. Each image is unique in comparison with the others. These choices give the images narrative power, anchoring them in human perspective.
Images to tell a story
Photographers choose what to include in the final version of their image to tell a story. In the Artemis II images, this human perspective comes out. In the “Earthset” photo, you see a striking juxtaposition of the Moon’s monochromatic, textured surface in the foreground against a slivered, bright Earth.
The choice to include both in the frame contrasts these objects literally and figuratively, inviting comparison. It creates a narrative where Earth is contrasted against the Moon – life is contrasted against the absence of it.
Another photo shows the nightside of the whole Earth, featuring the Sun’s halo, auroras and city lights. The choice to include the subtle framing of the window of the capsule in the lower left corner reminds the viewer where and how this image was captured: by a human, inside a capsule, hurtling through space. That detail grounds the photograph in the human perspective.
Both photos are reminiscent of Earthrise and the Blue Marble. These past images hold a place in the global collective consciousness, shaped by a shared historical moment.
The Artemis II photographs are anchored in this collective moment of lived human experience, yet also shaped by each astronaut’s viewpoint. The crew’s unique perspectives exemplify photography’s transformative power by inviting viewers to engage emotionally and intellectually with their journey. These photographs share the astronauts’ awe and wonder and affirm the value of human creativity and its ability to connect us in a captured moment.
Christye Sisson, Professor of Photographic Sciences, Rochester Institute of Technology
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
