Some unwelcome visitors from North America have been turning up in the waters off the coast of Great Britain.

    North American lobsters (龙虾) have been found in the North Sea (between Great Britain and Northwest Europe), far from their own habitat. The lobsters usually live along the eastern coast of Canada and the United States.

    It is impossible that the lobsters could have made the 5,600-kilometre journey on their own. They were probably brought to Britain and then got away from containers. Some of the lobsters that were caught had elastic bands (松紧带) holding their legs shut, like lobsters that are kept in containers in stores or restaurants.

    Many may have been “set free” from some ships passing through the area. Sometimes passengers order a live lobster from a tank in the dining room and then ask the waiter to throw it overboard instead of cooking it.

    According to official records, 26 North American lobsters have been caught in waters off Great Britain since 1988. However, it is believed many more have been found but not reported.

    It is against the law to let North American lobsters come into British waters. If they settle down in European waters, it would be bad for the local lobsters. The two live in the same place and eat the same food. But North American lobsters are larger, stronger and more aggressive (好斗的) than European lobsters, and they produce young more quickly.

    As a result, they could take food and space away from the local lobsters, and from other types of shellfish that live in the same area. These lobsters may also carry diseases that could harm the local lobsters.

    Most animals have little connection with animals of a different kind, unless they hunt them for food. Sometimes, however, two kinds of animals come together in a partnership (伙伴关系) which is good for both of them. You may have noticed some birds sitting on the backs of sheep. This is not because they want a ride, but because they find easy food in the parasites (寄生虫) on sheep. The sheep allow the birds to do so because they remove the cause of discomfort. So although they can manage without each other, they do better together.

    Sometimes an animal has a plant partner. The relationship develops until the two partners cannot manage without each other. This is so in the corals(珊瑚) of the sea. In their skins they have tiny plants which act as “dustmen”, taking some of the waste products from the coral and giving in return oxygen which the animal needs to breathe. If the plants are killed, or are even prevented from receiving light so that they cannot live normally, the corals will die.

    Last week my youngest son and I visited my father at his new home in Tucson, Arizona. He moved there a few years ago, and I was eager to see his new place and meet his friends.

My earliest memories of my father are of a tall, handsome successful man devoted to his work and family, but uncomfortable with his children. As a child I loved him; as a school girl and young adult I feared him and felt bitter about him. He seemed unhappy with me unless I got straight A's and unhappy with my boy- friends if their fathers were not as "successful" as he was. Whenever I went out with him on weekends, I used to struggle to think up things to say, feeling on guard.

    On the first day of my visit, we went out with one of my father's friends for lunch at an outdoor cafe. We walked around that afternoon, did some shopping, ate on the street table, and laughed over my son's funny facial expressions. Gone was my father's critical air and strict rules. Who was this person I knew as my father, who seemed so friendly and interesting to be around? What had held him back before?

    The next day my dad pulled out his childhood pictures and told me quite a few stories about his own childhood. Although our times together became easier over the years, I never felt closer to him than at that moment. After so many years, I'm at last seeing another side of my father. And in so doing, I'm delighted with my new friend. My dad, in his new home in Arizona, is back to me from where he was.

    On a clear night, you can see a sky paced with stars. But you can't see planets orbiting any of these stars, even with the strongest Earth—based telescopes. Astronomers reported that they discovered seven Earth—sized planets orbiting a nearby star called TRAPPIST – 1 in February. They had to rely on indirect evidence to tell them that the planets are there. By doing some math, they figured out the number of planets and the distance of their orbits.

    TRAPPIST – 1 is a red dwarf （红矮星）, much smaller than our sun, but larger than Jupiter (木星). If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. This star is one of our closest neighbors, just like the moon to the earth in space.

    When astronomers using Earth-based telescopes to study TRAPPIST – 1,they noticed that every once in a while, it became slightly dim（昏暗）. They decided that a planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.

    By making careful observations, astronomers expected to get a rough idea of the planet's size from the pattern of dimming light. But the light level changed often and not at evenly spaced (均匀间隔的) times. The astronomers had to conclude they were looking at more than one planet! To get additional data, NASA's spritzer Space Telescope measured TRAPPIST –1's brightness nearly continuously for 20 days, catching 34 crossings of planets in front of the star. Sorting through the mess of data, the astronomers found that the innermost planet completes its orbit in 1.5 Earth days, while the outermost planet takes 20 days. Once you know how long it takes each planet to complete an orbit, you can work out how far it is from the star compared with the other planets.

    The TRAPPIST – 1 planets are not alone. So far, astronomers have found more than 3,400 planets that orbit other stars.

    It seems that in many places storms visit more often. When a storm is coming, most people leave the area as quickly as possible and head for safety. But there are a few people who will get into their cars and go straight for the center of the storm. These people are willing to risk being killed by floods or 100-kilometer-an-hour winds for the excitement of watching the storm close up.

    "Storm chasing" is becoming an increasingly popular hobby, especially in the Midwest of the United States, where there are frequent storms between March and July. A storm chaser begins the day by checking the Internet for the latest weather reports, and then drives up to 1,000 kilometers to where the storm will be and waits for it to develop.

    Although anyone can do it, storm chasing is extremely dangerous. The power of a big storm can throw a cow into the air or destroy a whole house in seconds. Storm chasers are also often hurt in accidents caused by driving in a heavy rain. If you are a beginner, it is much safer to join a group for storm-chasing vacations during the storm season.

    Even then, storm chasing is not all adventure and excitement. "Storm chasing is 95% driving," says Daniel Lynch, who spends most of his summer storm-chasing. "Sometimes you can sit around for hours waiting for something to happen, and all you get is blue sky and a few light showers."

    However, for storm chasers, it is all worth it. "When you get close to a storm, it is the most exciting sight you will ever see in your life," says Jasper Morley. "Every storm is an example of the power of nature. It is the greatest show on Earth."

My Favorite Sweater

By Bonnie Highsmith Taylor