Imagine a perfect day: the weather is good and everything seems fine. When, suddenly, your mobile phone loses its signal, the television has no programs, and you can’t get online with your computer.

What has happened? These are just the types of problems a solar storm （太阳风暴） might cause.

You may not think of storms as putting our society in danger. But today, a solar storm is as serious as other bad events, such as earthquakes.

A solar storm is caused by solar flares （太阳耀斑） large explosions （爆炸） near the sun that can give off lots of energy. The strong energy can stop the satellite systems （卫星系统） that control our computers, telecom networks and so on. These storms can even cause the power to go out for weeks or months.

In the past few months, scientists have recorded some of the strongest sun flares in years. The most recent one happened around Valentine’s Day, 2011. It caused radio and satellite signals to go down in some northern cities in China.

“Solar flare activity is going to be much worse than what we’ve seen in the past. We’re not talking about a few cities losing power, it could be half of the country, maybe more. ”SolarStormWarning.com, a US website about space weather, warned. Scientists say that little can be done to predict such a storm.

Governments around the world are trying to work together before the next storm, although they are not sure when that may happen.

A strong storm hit the town of Carlton. Some people had cuts and bruises (青肿)，but no one was badly hurt. The storm destroyed many buildings and bridges. So some people become homeless.

The people of Carlton helped one another put their town back together. One of those people was Leah Torres. Leah had an idea to collect food, clothing and other items, such as soap, dishes and towels, for people in need. Leah felt happy that she could help.

Leah was proud of her town. She decided to write a letter to the president of the United States. In the letter she told him about her town’s efforts (努力). She said that the nation might be able to solve its problems if people followed Carlton’s example, Leah didn’t tell anyone about her letter. Half a month later, when Leah and her parents turned on the television one day, the president was giving a speech. He began to read from a letter. Suddenly Leah recognized (认出) the sentences.

“That’s my letter!” she told her parents .

The next day Leah got a call from the White House. An assistant to the president was on the phone. “The president wants me to thank you for your letter,” he said. “He agrees with you that people should work together. He says that one person can make a difference in a town. And sometimes he can make a difference in a whole country. ”