A person standing under the starry sky next to large rock formation in the middle of the desert

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The Darkest Places on Earth

At spots like Arches National Park in Utah, you can see stars and planets. But scientists fear our beautiful night sky might be disappearing.  

    Imagine gazing at a dark night sky. It’s covered in thousands of sparkling stars. A band of glittery white light stretches across the heavens. That’s our galaxy, the Milky Way. You can even see other planets! 

    This view greets lucky visitors at Arches National Park in Utah. At night, it is one of the darkest places on Earth. But most people don’t see such a dazzling night sky. In fact, they don’t see much in the sky at all. 

    The world is running out of places dark enough to see stars. When the sun sets, people turn on powerful outdoor lights. They light up homes, office buildings, and sports stadiums. The beams often shine even when not needed. This overuse of artificial light is called light pollution. 

    Light pollution affects the whole planet. That’s why people are taking steps to save the world’s darkest skies. 

    Imagine a dark night sky. It’s filled with thousands of stars. They create a band of white light. That’s our galaxy. It’s called the Milky Way. You can see other planets too!  

    You can see this view at Arches National Park. The park is in Utah. At night, it is one of the darkest places on Earth. But most people don’t see a night sky like this. They don’t see much in the sky at night. 

    The world is losing places that are dark at night. When the sun sets, people turn on outdoor lights. They light up homes and office buildings. They light up sports stadiums. People turn on lights that are not needed. Too much artificial light is called light pollution. 

    Light pollution affects the whole planet. That’s why people are trying to save the world’s darkest skies. 

    Imagine gazing up at a dark night sky that is covered in thousands of sparkling stars. A band of glittery white light—our galaxy, the Milky Way—stretches across the heavens. You can even spot other planets! !

    This is the view that greets lucky visitors at Arches National Park in Utah. At night, this park is one of the darkest places on Earth. But most people aren’t lucky enough to see such a dazzling night sky. In fact, they see hardly anything in the sky. 

    The world is running out of places dark enough to see stars. When the sun sets, people turn on powerful outdoor lights. They light up homes, office buildings, and sports stadiums. Even when they aren’t needed, beams of light still shine in many places. This overuse of artificial light is called light pollution. 

    The whole planet is affected by light pollution. That’s why people are taking steps to save the world’s darkest skies.  

Why We Need Darkness

The Museum of Modern Art. Acquired through the Lillie P. Bliss Bequest. Digital Image ©The Museum of Modern Art/Licensed by SCALA/Art Resource, NY.

    Why should we protect the night sky? For billions of years, Earth’s darkness has helped us—and other creatures—survive.

    Before we began using electricity, the night sky was lit only by the moon and stars. Sailors used the stars to navigate while at sea. Stars helped people mark the passage of time too.

    Artists also took inspiration from the night sky. In 1889, Vincent van Gogh painted his view of glowing stars. It became one of the world’s most famous paintings, The Starry Night.

    Today, the loss of darkness affects humans in many ways. Darkness tells our bodies that it’s time to go to bed. Without it, people can have a hard time sleeping. 

    Animals depend on dark skies too. Baby sea turtles, for example, hatch at night on beaches. The starlight shining on the waves guides them as they crawl to the ocean. If there’s too much artificial light, the turtles can lose their way.

    Why should we protect the night sky? For billions of years, Earth’s darkness has helped us—and other creatures—survive.

    Before electric lights, the night sky was lit only by the moon and stars. Sailors used the stars to navigate while at sea. People tracked the passage of time using stars.

    Artists were inspired by the night sky. In 1889, Vincent van Gogh painted his view of the stars. It’s called The Starry Night. It’s a very famous painting.

    Today, the loss of darkness affects us in many ways. Our bodies know to go to bed when it’s dark. Without darkness, people can have a hard time sleeping. 

    Animals need dark skies too. For example, baby sea turtles hatch at night. They hatch on beaches. They see the starlight shining on waves in the ocean. They go toward the waves. But the turtles can go the wrong way if there is too much artificial light.

    Why protect the night sky? For billions of years, Earth’s darkness has helped us—and other creatures—survive.

    Before we began using electricity, only the moon and stars lit the night sky. While at sea, sailors used the stars to navigate. Stars also helped people mark the passage of time.

    Artists also took inspiration from the night sky. In 1889, Vincent van Gogh painted The Starry Night. His view of glowing stars became one of the world’s most famous paintings.

    Today, humans are affected in many ways by the loss of darkness. Darkness tells our bodies that it’s time to go to bed—so without it, people might struggle to fall asleep. 

    Animals depend on dark skies too. Baby sea turtles, for example, hatch at night on beaches and crawl to the ocean, guided by starlight shining on the waves. If there’s too much artificial light, the turtles can lose their way.

Protecting the Night

    At least 2,500 stars can be seen from Earth. But people who live in cities often see fewer than a dozen. The sight of a natural dark sky is so rare that it can be confusing. 

    Once, all the electricity went out in Los Angeles, California. The sky turned dark. People called 911 to report a strange object floating above. It turned out to be the Milky Way!

    A group called the International Dark-Sky Association (IDA) is working to save our night skies. It has named nearly 200 “Dark Sky Places” around the world. How do these places stay dark? They follow rules. For example, they use outdoor lighting only when needed. They also make sure light bulbs are not too bright. 

    No matter where you live, there’s something you can do to help. It’s as easy as flicking a switch. “Light is a resource, just like water. We shouldn’t waste it,” says Ashley Wilson of the IDA. “Turn it off when you’re not using it.” 

    From Earth, we can see at least 2,500 stars. But in cities, people see fewer than 12. It’s rare to see a natural dark sky. It can be confusing. 

    Once, the electricity went out in Los Angeles, California. The sky turned dark. People called 911. They reported a strange object in the sky. What was it? The Milky Way!

    A group called the International Dark-Sky Association (IDA) is working to save our night skies. It has named nearly 200 places as “Dark Sky Places.” These places follow rules to stay dark. They use outdoor lighting only when needed. They use light bulbs that are not too bright. 

    You can help too. “Light is a resource, just like water. We shouldn’t waste it,” says Ashley Wilson of the IDA. “Turn it off when you’re not using it.” •

    At least 2,500 stars can be seen from Earth, but people who live in cities often see fewer than a dozen. The sight of a natural dark sky is so rare that it can be confusing. 

    Once, all the electricity went out in Los Angeles, California, and the sky turned dark. People called 911 to report a strange object floating above. What was it? The Milky Way!

    A group called the International Dark-Sky Association (IDA) is working to save our night skies. It has named nearly 200 “Dark Sky Places” around the world. These places stay dark by following rules. For example, they use outdoor lighting only when needed, and they make sure light bulbs are not too bright. 

    No matter where you live, helping to save the night sky is as easy as flicking a switch. “Light is a resource, just like water. We shouldn’t waste it,” says Ashley Wilson of the IDA. “Turn it off when you’re not using it.” •

Jim McMahon/Mapman ® 

Lights Out
Utah has the most “Dark Sky Places” in the world. 

The Brightest Place on Earth

Hong Kong is famous for its dazzling lights. But is it time to dim them?  

JSean Pavone/Alamy Stock Photo 

Nattee Chalermtiragool/Shutterstock.com

    Picture it: You’re in Hong Kong, a city in China. Every night after the sun goes down, crowds gather near a harbor. The clock strikes 8 p.m. A single skyscraper flashes a message: Get ready. 

    In the next moment, colorful lights shine from more than 40 buildings. These lights pulse in time with music. For 10 minutes, spotlights glow. Laser beams dance around the harbor. 

    Imagine this: You’re in Hong Kong. That’s a city in China. The sun goes down. The clock strikes 8 p.m. One skyscraper flashes a message in lights: Get ready.

    Then lights shine from more than 40 buildings. These lights flash in time with music. For 10 minutes, spotlights beam light around the harbor. 

    Picture it: You’re in Hong Kong, a city in China. Every night after the sun goes down, crowds gather near a harbor. The clock strikes 8 p.m., and a single skyscraper flashes a message: Get ready.

    In the next moment, colorful lights from more than 40 buildings begin pulsing in time with music. For 10 minutes, spotlights glow and laser beams dance around the harbor. 

ESB Professional/Shutterstock.com

    But the show doesn’t stop there. Hong Kong is famous for buzzing neon signs and bright billboards. These lights burn all night long. 

    It’s no surprise that the city has one of the world’s worst light pollution problems.

    But the show is not over. Hong Kong is famous for bright neon signs and billboards. These lights burn all night long. 

    This city has one of the world’s worst light pollution problems.

    But the show doesn’t stop there. Hong Kong is famous for buzzing neon signs and bright billboards, which burn all night long. 

    It’s no surprise that the city has one of the world’s worst light pollution problems.

Let There Be Light

    Until the late 1800s, people used candles, torches, oil lamps, or gas lamps to see after dark. Then in 1879, Thomas Edison invented the electric light bulb. 

    The light bulb allowed the world to have light around the clock. The use of streetlamps and other outdoor lighting began to increase. People could now work and play at all hours. 

    Today, most of our artificial light is from LED bulbs. LEDs use less energy than other bulbs. They’re much brighter—and cheaper to keep on too. The low cost has led many people to use more light at night, even where it isn’t needed. 

    You’ve probably seen buildings or sports fields that are brightly lit all the time. Light pollution around the world has increased by at least 49 percent over the past 25 years. 

    Until the late 1800s, people used candles, torches, oil lamps, or gas lamps to see after dark. Then in 1879, Thomas Edison invented the electric light bulb. 

    The light bulb allowed people to have light all day and all night. The use of streetlamps increased. People could now work and play at all hours. 

    Today, most of our artificial light is from LED bulbs. LEDs use less energy than other bulbs. They’re much brighter. They’re cheaper to keep on too. So many people use more light at night, even where it isn’t needed. 

    You’ve probably seen buildings that are brightly lit all the time. Light pollution has increased by at least 49 percent over the past 25 years. 

    Until the late 1800s, people used candles, torches, oil lamps, or gas lamps to see after dark. Then in 1879, Thomas Edison invented the electric light bulb. 

    Because of the light bulb, the world could have light around the clock. The use of streetlamps and other outdoor lighting increased. People could now work and play at all hours. 

    Today, most of our artificial light is from LED bulbs, which use less energy than other bulbs. They are much brighter and are cheaper to keep on. The low cost has led many people to use more light at night, even where it isn’t needed. 

    Buildings and sports fields are brightly lit all the time, as you’ve probably seen. Over the past 25 years, light pollution around the world has increased by at least 49 percent. 

How Much Is Enough?

    We need light at night for many reasons. For one, it helps us travel safely. (Can you imagine biking home at night with no streetlights?) Shops and restaurants also use bright signs to attract customers.

    But in places like Hong Kong, experts say there is too much artificial light. People cover their windows with thick curtains so they can sleep. Other creatures are affected too. Some animals do certain activities, such as hunting, only in darkness. The bright light confuses them. Many birds are drawn toward the lights and crash into them. 

    Plants like trees also suffer. They sense what season it is by the length of daylight. That lets them know when to shed their leaves or to blossom. Artificial light can lead plants to bloom too early or keep their leaves too long. 

    We need light at night for many reasons. It helps us travel safely. (Would you want to bike home at night with no streetlights?) Shops and restaurants also use bright signs to attract customers.

    But in places like Hong Kong, experts say there is too much artificial light. People cover their windows with thick curtains so they can sleep. Other creatures are affected too. Some animals hunt only in darkness. The bright light confuses them. Birds are drawn toward the lights and crash into them. 

    Trees and other plants suffer too. They sense what season it is by the length of daylight. That tells them when to shed their leaves. Artificial light can lead plants to keep their leaves too long. 

    Light is important to have at night for many reasons. For example, it helps us travel safely. (Can you imagine biking home at night with no streetlights?) Shops and restaurants also use bright signs to attract customers.

    But experts say there is too much artificial light in places like Hong Kong. People cover their windows with thick curtains so they can sleep. Other creatures are affected too. Animals that do certain activities, such as hunting, only in darkness are confused by the bright light. Many birds are drawn toward the lights and crash into them. 

    Plants like trees also suffer. They sense what season it is by the length of daylight, which lets them know when to shed their leaves or to blossom. Artificial light can lead plants to bloom too early or keep their leaves too long. 

Jim McMahon/Mapman ® 

Lights on  
Hong Kong is a city in southern China. It has one of the world’s worst light pollution problems.

Finding the Balance

    Many cities around the world have passed laws to help lower light pollution. But Hong Kong has no such laws. 

    Scientist Jason Pun studies Hong Kong’s light pollution. He believes there can be a balance between too much light and not enough. “There are easy solutions,” he says. 

    For example, city officials could turn on fewer streetlights. They could also set a limit for how bright public lights can be. “I hope to get the night sky back,” says Pun. 

    Many cities around the world have passed laws to help lower light pollution. But Hong Kong has no such laws. 

    Scientist Jason Pun studies Hong Kong’s light pollution. “There are easy solutions,” he says.

    For example, city officials could turn on fewer streetlights. They could also set a limit for how bright public lights can be. “I hope to get the night sky back,” says Pun. 

    Many cities around the world have passed laws to help decrease light pollution—but Hong Kong has no such laws. 

    Scientist Jason Pun, who studies Hong Kong’s light pollution, believes there can be a balance between too much light and not enough. “There are easy solutions,” he says.

    For example, city officials could turn on fewer streetlights. They could also set a limit for how bright public lights can be. “I hope to get the night sky back,” says Pun. 

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