Today, nearly five hundred weather stations in sixty countries receive satellite pictures.  When they receive new pictures, the meteorologists compare（比较）them with earlier ones.  Perhaps they may find that the clouds have changed during the last few hours.  This may mean that the weather on the ground may soon change, too.  In their next weather forecast, the meteorologists can say this.
　 So the weather satellites are a great help to the meteorologists.  Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours.  Now they can make good forecasts for three or five days.  Soon, perhaps, they may be able to forecast the weather for a week or more ahead（提前）.

Are You Right Handed or Left Handed?

    Which hand do you use when write? About 8 to 15 percent of people are left handed. They often have to use tools that are designed for right-handed people. So it is difficult for left-handers to use most tools. If you are right handed, try this experiment: Take a knife with your left hand and try cutting a potato into pieces. Don't be surprised if you feel awkward（别扭的）.

    In the past, people thought it was strange to use the left hand. Young students looked down upon their left-handed classmates. Some children were even punished for using their left hand to write. But these days parents and teachers have accepted that. In almost every school in the world, left-handed students can use their left hand to write.

    What causes people to be left handed or right handed? Experts have searched long and hard on this. They conclude（得出结论） that left-handed people are left handed for the same reason that right-handed people are right handed. One out of every ten people just is a left-handed people are right handed. One out of every ten people just is a left-hander. It's simply like the color of our eyes – some people have brown eyes, while some others have black eyes.

    However, may researchers think that left-handers and right-handers are different in some aspects. Right-handers are more talkative and outgoing than left-handers. Many right-handed people understand spoken words better. For example, after they listen to directions to a supermarket, they can find it easily. Right-handers are good at organizing people, too. They are also better basketball guards. Just ask Yao Ming.

    Research shows that left-handers are creative and artistic. Many famous performers, like Jim Carrey and Paul McCartney, are left handed. Many left-handers learn better visually（在视觉方面）. In art, both Leonardo da Vinci and Michelangelo were left handed. In music, Ludwig van Beethoven was left handed. In science, you find Newton and Einstein. The left-handed people are also really good at tennis and other single sports.

    If you prefer one hand, but you are still good at writing with the other, you are mixed. Research shows mixed-handers can remember everyday things better than other people. What did you eat for lunch two weeks ago? If you're mixed handed, you can probably remember.

    Are you a big fan of E. T. (Extraterrestrial) or aliens? Then you should read Extraterrestrial Civilizations (《地球以外的文明世界》) by American writer Isaac Asimov (1920~1992). In his 1979 book, Asimov looked at whether there is life beyond the Earth. He also talked about how we might be able to communicate with aliens someday. Asimov even told us that there are possibly about 500, 000 civilizations (文明) in the galaxy(银河系). The book may be a little out of fashion since it came out in the 1970s. But you'll still enjoy the good reasoning (推理 ) and imagination of it. Asimov was a science fiction(科幻故事) master. His most famous works talk about the relationship between robots and humankind.

    Many scientists find that colors can change people's feelings. It's very interesting. Some colors can make people feel relaxed, and some colors can make people feel nervous. Now, this kind of knowledge is being used in many places. For example, school walls are always painted green because green makes students feel relaxed. It is also good for the students' eyes. Some books are also green or light blue for the same reason. Restaurant owners not only have to know how to make food, but also have to know how to make money. Here are some things they've learned from scientific studies. The color red makes people hungry. Many fast food restaurants have red furniture or walls. Soft colors like pink and light blue make people feel relaxed, so they spend more time eating. Loud music may be nice at first, but it soon makes people want to leave. Hard seats also make customers want to eat quickly and leave. Many restaurants, especially fast food restaurants, use this knowledge to make customers eat faster.