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.

September 2022

by Mary Kate Frank

galaxy

any of the large groups of stars that make up the universe

Our galaxy is made up of billions of stars, including the sun.

photo credit: struturesxx/Shutterstock

Gloved hands holding a test tube with yellow liquid inside

artificial

not natural; created by people

Lab workers used artificial ingredients to make this candle smell like apple pie.

photo credit: gkrphoto/Shutterstock

navigate

to find the way to get from place to place

I’m so glad my phone can help me navigate, because I get lost easily.

photo credit: AngieYeoh/Shutterstock

resource

a usable supply of something

In some parts of the world, fresh water is a resource that not everyone has.

photo credit: emerald_media/SHutterstock

Ants swarming a peanut butter and jelly sandwich

attract

cause someone or something to come closer

Leaving your food out overnight might attract ants.

photo credit: whitejellybeans/Shuitterstock

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.

Why We Need Darkness

Famous Van Gogh painting of swirling blues and yellows to show the night sky

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.

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.”

The Brightest Place on Earth

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

September 2022

by Mary Kate Frank

Buildings lit in different colors lighting the night sky and reflecting off the water

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.

brightly lit billboards written in a foreign language

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.

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.

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.

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.