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.
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 oblatespheroid. 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.Our distance from the Sun is not why we have seasons. NASA
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.
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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.Because of the tilt of the Earth, we are able to experience the seasons. Stephanie Spera
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.The Earth’s axis is always tilted at 23.5 degrees. Stephanie Spera
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.
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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.
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DoorDash Driver Arrested After Claiming Sexual Assault: What Really Happened?
A DoorDash driver who claimed she was sexually assaulted during a delivery is now facing felony charges after police say her viral video showed an unconscious, partially nude customer without consent. Here’s what investigators found and why the case is sparking national debate.
DoorDash delivery driver involved in a viral video controversy after claiming sexual assault; police say no assault occurred, and the driver now faces felony charges.
DoorDash Driver Arrested After Claiming Sexual Assault: What Really Happened?
A Viral Accusation Turns Into a Criminal Case
A routine food drop-off turned into a national controversy this month after a DoorDash delivery driver claimed she was sexually assaulted during a delivery — only to later be arrested herself following a police investigation. The incident, which quickly spread across TikTok and other platforms, has generated fierce debate over privacy, personal safety, and the power of viral video culture.
The driver, identified as Livie Rose Henderson, posted a video on social media in mid-October claiming that when she arrived at a customer’s home in Oswego, New York, she found the front door open and discovered a man “half-naked and unconscious” on his couch. She publicly described the moment as a sexual assault, saying she felt endangered and traumatized.
Her posts went viral almost immediately, drawing attention from millions of viewers and sparking outrage over the safety risks faced by gig workers — particularly women — who make deliveries to unfamiliar homes.
But the narrative took a dramatic turn.
Police: No Sexual Assault Occurred
According to the Oswego Police Department, an investigation found no evidence that Henderson was sexually assaulted. Instead, authorities say that she:
Entered the home without consent
Recorded the unconscious customer, who was partially nude
Posted the footage online, identifying him
Made claims police say were “false and misleading”
Investigators concluded the man was intoxicated and unconscious, not acting with intent or awareness. As a result, Henderson was arrested and charged with:
Second-degree unlawful surveillance (felony)
First-degree dissemination of unlawful surveillance images (felony)
Police emphasized that recording a person who is nude or partially nude inside their home — regardless of context — constitutes a violation of New York’s surveillance and privacy laws if done without permission.
DoorDash Drops the Driver
Henderson also claimed that DoorDash deactivated her account, something she described as retaliation for “exposing her assaulter.” But following her arrest, DoorDash stated that recording customers inside their homes violates company policy and local laws.
DoorDash said it cooperated with investigators but declined to comment further on personnel matters.
A Complicated Public Reaction
Social media reaction has been sharply divided:
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Sympathy for the driver
Many viewers initially supported Henderson, arguing that gig workers often deal with unsafe conditions and should not be forced to decide between finishing a delivery or backing away from a potentially threatening situation.
Backlash over privacy violations
Others argue that Henderson crossed legal and ethical boundaries by:
Entering a private residence
Recording a vulnerable, unconscious person
Posting it publicly
Accusing the individual of a crime without evidence
These actions, critics say, show the dangerous consequences of rushing to social media before police or professional investigators evaluate the facts.
The Larger Issue: Safety vs. Responsibility
This case highlights a broader tension in the era of app-based work and viral content:
Gig workers do indeed face unpredictable and sometimes unsafe situations.
Customers have a right to privacy in their homes.
Social media, meanwhile, rewards the fastest and most dramatic version of a story — even before the truth is known.
As the criminal process continues, Henderson’s case may set a new precedent for how privacy laws interact with the realities of delivery work and the instant visibility of online platforms.
Focuses on the legal perspective, privacy violations, and the potential consequences of posting sensitive content online.
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How China cleaned up its air pollution – and what that meant for the climate
How China cleaned up its air pollution: Beijing’s air quality went from hazardous to good while Delhi and Lahore still struggle. Discover how China dramatically reduced pollution since 2013—and why cleaner air may have unintended consequences for global warming and climate change.
Delhi: 442. Lahore: 334. Beijing: 16. These are the levels of PM 2.5, one of the principle measures for air pollution, on November 19. As Pakistanis and Indians struggle with hazardous air quality, in Beijing – a city once notorious for its smog – the air quality is currently rated as good. Ahead of the 2008 Beijing Olympics, the Chinese government was so concerned about pollution that it introduced temporary restrictions on cars, shut down factories and stopped work on some construction sites. The measures worked and one study later found that levels of air pollution were down 30% during the period when the temporary Olympic restrictions were in place. It would take a few more years before the Chinese government implemented a clean air action plan in 2013. Since then, China has achieved a dramatic improvement in its air quality. In this episode of The Conversation Weekly podcast, we speak to Laura Wilcox, a professor at the National Centre for Atmospheric Science at the University of Reading in the UK, to understand how China managed to clean up its air pollution. But Wilcox’s recent research uncovered some unintended consequences from this cleaner air for the global climate: the pollution was actually helping to cool the atmosphere and by taking it away, it may have accelerated global warming. Wilcox explains:
What we’re seeing is a removing of cooling that’s revealing warming that’s already there. So the air pollution isn’t the cause of the warming. It’s just letting us see stuff that we’ve already done.
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The Hong Kong high-rise fire shows how difficult it is to evacuate in an emergency
Hong Kong High-Rise Fire: The deadly Hong Kong fire exposes critical challenges in evacuating tall buildings. Learn why stair descent is slower than expected, how human behavior causes delays, and what modern safety features can save lives.
Evacuations of high-rises don’t happen every day, but occur often enough. And when they do, the consequences are almost always severe. The stakes are highest in the buildings that are full at predictable times: residential towers at night, office towers in the day. We’ve seen this in the biggest modern examples, from the World Trade Center in the United States to Grenfell Tower in the United Kingdom. The patterns repeat: once a fire takes hold, getting thousands of people safely down dozens of storeys becomes a race against time. But what actually makes evacuating a high-rise building so challenging? It isn’t just a matter of “getting people out”. It’s a collision between the physical limits of the building and the realities of human behaviour under stress.
It’s a long way down to safety
The biggest barrier is simply vertical distance. Stairwells are the only reliable escape route in most buildings. Stair descent in real evacuations is far slower than most people expect. Under controlled or drill conditions people move down at around 0.4–0.7 metres per second. But in an actual emergency, especially in high-rise fires, this can drop sharply. During 9/11, documented speeds at which survivors went down stairs were often slower than 0.3 m/s. These slow-downs accumulate dramatically over long vertical distances. Fatigue is a major factor. Prolonged walking significantly reduces the speed of descent. Surveys conducted after incidents confirm that a large majority of high-rise evacuees stop at least once. During the 2010 fire of a high-rise in Shanghai, nearly half of older survivors reported slowing down significantly. Long stairwells, landings, and the geometry of high-rise stairs all contribute to congestion, especially when flows from multiple floors merge into a single shaft. Slower movers include older adults, people with physical or mobility issues and groups evacuating together. These reduce the overall pace of descent compared with the speeds typically assumed for able-bodied individuals. This can create bottlenecks. Slow movers are especially relevant in residential buildings, where diverse occupants mean movement speeds vary widely. Visibility matters too. Experimental studies show that reduced lighting significantly slows down people going down stairs. This suggests that when smoke reduces visibility in real events, movement can slow even further as people hesitate, misjudge steps, or adjust their speed.
Human behaviour can lead to delays
Human behaviour is one of the biggest sources of delay in high-rise evacuations. People rarely act immediately when an alarm sounds. They pause, look for confirmation, check conditions, gather belongings, or coordinate with family members. These early minutes are consistently some of the costliest when evacuating from tall buildings. Studies of the World Trade Center evacuations show the more cues people saw – smoke, shaking, noise – the more they sought extra information before moving. That search for meaning adds delay. People talk to colleagues, look outside windows, phone family, or wait for an announcement. Ambiguous cues slow them even further. In residential towers, families, neighbours and friend-groups naturally try to evacuate together. Groups tend to form wider steps, or group together in shapes that reduce overall flow. But our research shows when a group moves in a “snake” formation – one behind the other – they travel faster, occupy less space, and allow others to pass more easily. These patterns matter in high-rise housing, where varied household types and mixed abilities make moving in groups the norm.
Why stairs aren’t enough
As high-rises grow taller and populations age, the old assumption that “everyone can take the stairs” simply no longer holds. A full building evacuation can take too long, and for many residents (older adults, people with mobility limitations, families evacuating together) long stair descents are sometimes impossible. This is why many countries have turned to refuge floors: fire- and smoke-protected levels built into towers as safe staging points. These can reduce bottlenecks and prevent long queues. They give people somewhere safe to rest, transfer across to a clearer stair, or wait for firefighters. Essentially, they make vertical movement more manageable in buildings where continuous descent isn’t realistic. Alongside them are evacuation elevators. These are lifts engineered to operate during a fire with pressurised shafts, protected lobbies and backup power. The most efficient evacuations use a mix of stairs and elevators, with ratios adjusted to the building height, density and demographics. The lesson is clear: high-rise evacuation cannot rely on one tool. Stairs, refuge floors and protected elevators should all be made part of ensuring vertical living is safer.Milad Haghani, Associate Professor and Principal Fellow in Urban Risk and Resilience, The University of Melbourne; Erica Kuligowski, Principal Research Fellow, School of Engineering, RMIT University, and Ruggiero Lovreglio, Professor in Digital Construction and Fire Engineering, Te Kunenga ki Pūrehuroa – Massey University This article is republished from The Conversation under a Creative Commons license. Read the original article.
STM Daily News is a vibrant news blog dedicated to sharing the brighter side of human experiences. Emphasizing positive, uplifting stories, the site focuses on delivering inspiring, informative, and well-researched content. With a commitment to accurate, fair, and responsible journalism, STM Daily News aims to foster a community of readers passionate about positive change and engaged in meaningful conversations. Join the movement and explore stories that celebrate the positive impacts shaping our world.
Gemma Ware, Host, The Conversation Weekly Podcast, The Conversation This article is republished from The Conversation under a Creative Commons license. Read the original article.
