On Sunday, April 22, people all over the world take times out to appreciate（珍惜）the earth that we all share. It's Earth Day a special day to learn about our planet（星球）and how to take care of it．(1) On Earth Day, some people listen to speeches about the environment. Others help clean up their offices or save water and electricity at home. Your parents may even decide to take a day off from driving their cars.
The idea for Earth Day came from a US Senator (参议员), who was worried about population and the health of plants and animals. And the idea quickly caught on (流行起来)．In 1970，the first Earth Day was celebrated. More than 20 million people in cities all over the US took part in. (2) Since then ， Earth Day has been used to educate people about their role in taking care of our planet.
Now, Earth Day has become a global celebration. In 1990, 200 million people from 140 countries took part in clean-ups, trees planting and other environmental events on Earth Day.
