Lesson 4 Earth, Our Only Home
Is It a Light Problem?
Look ____ this beautiful painting.
It was ____ by the famous Dutch artist Vincent van Gogh in 1889.
In Van Gogh's time, almost everyone could look up and see a ____ starry night sky.
Now, how many of us are as ____ as Van Gogh?
In fact, many people in ____ world cannot enjoy a starry night sky.
This is ____ because of light pollution.
Most of us are familiar
Most of us are familiar with air, water, ____ land pollution.
We ____ that they are serious problems, and we are taking action to solve them.
But did you know that light ____ also cause pollution?
Light pollution―too much light in the wrong ____ at the wrong time―is almost everywhere around the world.
It can have ____ effects on humans and wildlife.
According to a recent report, about 80% of the world's population lives ____ skies that are not dark enough at night.
Especially in ____ cities, people often cannot see a starry night.
They can ____ suffer from sleep problems because the natural rhythm of day and night is disturbed by artificial light.
Wildlife is threatened
Wildlife is threatened by light pollution, ____
Birds that migrate or hunt at night find their way by natural ____
but light in ____ cities can cause them to wander off course.
Every year millions of birds ____ after hitting buildings that have bright lights.
Sea turtles cannot easily find a place to lay eggs since beaches ____ too bright at night.
Also, many baby sea turtles die because artificial light draws ____ away from the ocean.
Clearly, light pollution is as serious ____ other forms of pollution.
____ have to find ways to solve the problem.
If we do not, ____ may see stars only in our dreams or paintings.