Since ancient times, human beings have looked up at the night sky. Comets (彗星) and meteors (流星) flying through the blackness were seen as signs from the gods. They were used to tell the future of human lives.

    In 2013, a meteorite shower hit an area in Russia. It injured around 1,200 people. In ancient times, this would have been a strange and terrible experience. Today, thought, science offers simple explanations for the occurrence (事件).

    Meteorites are small pieces of debris (碎片) that float around in space. Sometimes, they come near a planet, such as Earth. When they enter our atmosphere, they often heat up and become very bright. This is why they are sometimes called “fireballs”. They are usually made of metals, such as iron (铁), and other minerals (矿物). The Russian meteorites were stony, with iron making up 10 percent of them.

    Meteorite showers, such as that in Russia, happen when a large meteor enters the Earth's atmosphere and, due to heat, breaks up into small parts. Most of these are very small — smaller than a grain of sand — and so don't even make it to the ground. But others can cause a lot of damage.

    The meteor in Russia weighed 10 tons when it entered our atmosphere, and broke up about 20-30 miles (30-50 km) above ground. The sky was filled with bright lights and loud noises. Many windows were broken. The damage cost Russia around 206 million yuan.

    Do you believe that only boys do well in science? Does it seem that girls have better language skills than boys? In your opinion, are boys better at building things? If your answer to each of those questions is" Yes", you are right, according to an article in Current Science. There are exceptions(例外),but here are the facts.

    Usually, boys score higher in tests about math, while girls do better in tests about words, spelling and memory. But these differences may not always be true. In the future, a person's abilities may not be decided by sex. As one scientist says, "Nothing is impossible for a person to be or do."

    A recent study by Jerome Kagan, a scientist at Harvard University is studying the watching ability of children who are 10 months old. Baby boys and baby girls are watching "show" while seated on their mothers' laps. In Act One of the show, an orange-colored ball is lifted from a blue box and moved slowly. Then it is returned to the box. This is repeated six times. Act Six is almost the same, except that the orange ball is smaller. Baby boys do not seem to notice the difference in the size of the ball, but girls immediately become excited and begin to make noises that sound like language.

    It's also known that baby girls usually talk at an earlier age than baby boys do. Scientists believe that the left side of the brain develops faster in girls than in boys. As a result, by the time they start to go to school, little girls have an advantage that boys don't have, but what have the boys been doing in the years before starting school? They have been developing something called aggression. An aggressive person feels strong and independent. He is often the first one to start a fight. It is said that aggression is caused by hormones(荷尔蒙). Scientists believe that hormones are not the only cause. They say aggression in boys is also caused by mothers.