Beijing, July 18 (Reporter Shangguan Yun) What if one day an asteroid hits the earth? This may be a scene imagined by many science fiction lovers. Earlier, it was reported that an asteroid might hit the earth on September 9 this year, but this possibility was finally ruled out.

　　On the 17th, "Asteroids will not hit the Earth in September" boarded a hot search in Weibo, which once again triggered a heated discussion: What is the "asteroid" we often talk about? What will happen if it collides with the earth?

　　The probability of "one in seven thousand" colliding with the earth

　　The hot search for "asteroids will not hit the earth in September" is related to an announcement issued by the European Space Agency on the 16th. According to media reports, the announcement pointed out that a mysterious asteroid discovered more than ten years ago was originally thought to have a small probability of hitting the earth on September 9 this year, but the latest observation data ruled out this possibility.

　　It is understood that this asteroid was discovered by astronomers in 2006, so it was code-named 2006 QV89. According to the observation data at that time, it had a probability of colliding with the earth on September 9 this year.

　　However, this asteroid was only observed in a short period of 10 days, and then mysteriously "disappeared". Astronomers never observed it again, which made it difficult to accurately calculate its current position.

　　Therefore, in order to judge whether the original observation results of QV89 "collision with the Earth" in 2006 are accurate, researchers have pondered a method: first, assume that the asteroid is still in the orbit that may collide with the Earth, and then observe its possible position in the sky on July 4 and 5, but found nothing.

　　Based on all kinds of data, this asteroid was finally considered to be no threat to the earth.

　　What the hell is an asteroid?

　　As the name implies, asteroids are celestial bodies in the solar system that move around the sun like planets, but their volume and mass are much smaller than those of planets.

　　"In 2006, scientists defined planets, asteroids and dwarf planets. For example, the earth is a planet, which basically lives alone, revolves around the sun, and has a relatively round shape. A typical dwarf planet is Ceres, and they are ‘ Live in groups ’ Yes, there are a bunch of celestial friends in the orbit. " Sun Zhengfan, a doctor of astrophysics and a popular science writer, said.

　　As for asteroids, compared with the first two, they are simply a group of strange little guys. Sun Zhengfan explained that asteroids also revolve around the sun, but they are not round in shape, and they are grotesque in shape, big and small.

　　According to public information, as of 2018, about 1.27 million asteroids have been discovered in the solar system, but due to the limitations of observation methods and other factors, this may be only a small part of all asteroids.

　　"If you search for near-earth asteroids or near-earth asteroids on the Internet, the number of them mentioned in relevant popular science articles will definitely surprise people." Sun Zhengfan said.

　　Asteroids and the mystery of dinosaur extinction

　　The powerful destructive power of asteroids hitting the earth can be known from scientists’ discussion on the mystery of dinosaur extinction. There is a well-known saying that an asteroid hit the earth about 66 million years ago was the direct cause of dinosaur extinction.

　　Specifically, this view holds that when an asteroid hit the earth, it triggered a huge tsunami, and the ocean on the surface of the earth suddenly rolled, but this was not the only disaster faced by dinosaurs.

　　The impact raised a lot of hot rocks and dust, which triggered a forest fire. Countless flying dust covered the sky, and the earth’s surface was not exposed to sunlight for many years. The global climate became cold and creatures became extinct on a large scale. Dinosaurs couldn’t adapt to the drastic climate change, and in addition, they were short of food and eventually went extinct.

　　"There are a pair of astronomers and their sons in the United States. In the strata around 66 million years ago, a metal element was found to have a very high content, but normally it has very little content in the rocks of the earth." Sun Zhengfan said, therefore, astronomers and their sons speculated that this metal element in the stratum exceeded the standard because an asteroid with a diameter of about 10 kilometers hit the earth at that time.

　　Of course, there are many different opinions about the reasons for the extinction of dinosaurs, such as volcanic eruption and so on. Sun Zhengfan introduced that some paleontologists believe that the extinction of dinosaurs is not a sudden event, but a process. Because of the long time, it is difficult to find a complete chain of evidence for many claims about the extinction of dinosaurs. The most popular one is "an asteroid hit the earth".

　　The disaster caused by "close contact"

　　In fact, people are worried about the "close contact" between asteroids and the earth because of the disaster and destructive power they may bring after hitting the earth.

　　For example, according to media reports, on February 15, 2013, an asteroid with a diameter of about 20 meters exploded over Chelyabinsk, Russia, which indirectly damaged more than 3,000 buildings and injured more than 1,600 people.

　　Astronomically, an object whose orbit is within 1.3 astronomical units from the sun (1 astronomical unit is the average distance between the sun and the earth, which is about 150 million kilometers) and whose orbit distance from the earth is less than 0.3 astronomical units is a near-earth object, which is a collection of near-earth asteroids and near-earth comets.

　　Among them, the potential impact with a diameter of more than 140 meters and the minimum distance from the earth orbit within 0.05 astronomical unit threatens celestial bodies and poses a direct threat to the earth.

　　"An asteroid with a larger diameter can easily cause serious disasters when it hits the earth." Sun Zhengfan explained that "asteroid impact on the earth" is a high-risk event, such as the impact that is thought to have led to the extinction of dinosaurs. There is still a huge crater in Mexico’s Yucatan Peninsula, half on land and half in the sea.

　　Asteroids are terrible? There is no need to be overly anxious.

　　Based on the possible serious consequences of an asteroid’s visit, the news that an asteroid may hit the earth often causes many people’s worries. But Sun Zhengfan said that there is no need to be too anxious about this.

　　"First of all, it can cause extremely serious consequences ‘ Asteroids hit the earth ’ It’s a small probability event, and secondly, our earth has the atmosphere ‘ Protector ’ 。” Sun Zhengfan said.

　　Data Map: The picture shows beijing aerospace control center’s real-time monitoring and control mission of "Chang ‘e II" flying over an asteroid on December 13th. Sun zifa

　　He explained that the earth is moving in space, and there are always a huge number of things falling on it, mostly in the form of dust, or just like pebbles, some asteroids burn out in the atmosphere. "There are no people in most parts of the earth, such as the sea and the desert. Therefore, it does not have much impact on human beings. "

　　Sun Zhengfan also admitted that with the current scientific and technological means, it is still difficult to accurately calculate the running paths of asteroids that may cause harm to the earth, and "we can only estimate their size and quality by reflecting light, and this data itself has errors".

　　"Preventing doomsday asteroids is a very important job." Sun Zhengfan said, "Humans can unite to develop aerospace technology and prevent this major disaster through early warning."

　　Recently, the General Office of the Ministry of Education issued the Notice on Further Strengthening the Sleep Management of Primary and Secondary School Students (hereinafter referred to as the Notice), further emphasizing the need to ensure adequate sleep time for students and refining relevant management measures. The "Notice" requires that students’ sleep monitoring and supervision should be strengthened, students’ sleep status should be included in the physical health monitoring and education quality evaluation and monitoring system, included in the scope of daily supervision and the supervision and evaluation of the government’s performance of educational duties, and a supervision and reporting telephone or network platform should be set up to ensure that the requirements are in place and effectively ensure students’ good sleep.

　　We should fully improve our understanding of the importance of sleep health.

　　The Notice puts forward three "important times". The first is the necessary sleep time. Primary school students should sleep for 10 hours a day, junior high school students should sleep for 9 hours and senior high school students should sleep for 8 hours. The second is the school schedule. Class starts at 8: 20 in the morning in primary schools and 8: 00 in middle schools. At the same time, it is emphasized that schools should not require students to arrive at school in advance, and necessary lunch breaks should be guaranteed if conditions permit. The third is bedtime at night. Pupils are generally not later than 21: 20, junior high school students are generally not later than 22: 00, and senior high school students are generally not later than 23: 00. At the same time, guide parents and students, make schedules for students’ work and rest, promote autonomous management, work and rest regularly, and go to bed on time. Only by controlling the school schedule and students’ bedtime at night can students’ necessary sleep time be effectively guaranteed.

　　Lv Yugang, director of the Department of Basic Education of the Ministry of Education, pointed out that schools can manage the morning classes. The more important time is bedtime at night. Some bad living habits, such as watching mobile phones, playing computers and indulging in the Internet, affect students’ bedtime. Whether you can sleep at night depends on the students’ self-management ability and the guidance, cooperation and consultation between parents and students. In this process, we should strengthen the education of students, strengthen the guidance of parents, and strive to ensure that the bedtime at night can be achieved.

　　Zhu Dongbin, deputy director of the Department of Basic Education of the Ministry of Education, said that places and schools with conditions should guarantee students the necessary lunch break. We also encourage all localities and schools to explore all kinds of good experiences and practices that help students sleep according to the actual situation and school facilities. Sleep is a big event, and we should be able to reach a consensus that we should not lose big because of small things, let alone give up the basics.

　　Jiang Fan, secretary of the Party Committee of Shanghai Jiaotong University School of Medicine, director of the Center for Diagnosis and Treatment of Children’s Sleep Disorders, and head of the Children’s Sleep Study Group of the Sleep Medicine Committee of the Chinese Medical Doctor Association, said: The majority of primary and secondary schools, teachers, parents and students should fully raise their awareness of the importance of sleep health, and enhance their understanding of the requirements of sleep time required by different age groups and healthy sleep habits. According to the Notice, the length of sleep students should get every day is consistent with the internationally recognized recommended length of sleep. This requirement is implemented on individuals, and parents also need to master individual differences. Primary school students need 9-12 hours of sleep every day, and middle school students need 8-10 hours. Teachers and parents can strengthen communication with their children, work out schedules suitable for individual students together, and at the same time, they can know whether they sleep well or not from the aspects of children’s mental state and self-feeling, and make adjustments to the schedules according to the actual situation.

　　Sacrificing sleep time for study can’t be exchanged for improving academic performance.

　　In view of the external factors affecting students’ sleep, the Notice puts forward three "interruption mechanisms", requiring homework, off-campus training and games to make way for students’ sleep.

　　The first is the "interruption" of homework, which requires primary school students to basically complete their written homework in school, and middle school students to complete most of their written homework in school. If individual students have not finished their homework by bedtime after efforts, parents should urge them to go to bed on time and not stay up late to ensure adequate sleep. Of course, teachers should conduct targeted analysis, strengthen counseling, and adjust the content and amount of homework if necessary. The second is the "interruption" of off-campus training time, which requires that the off-campus offline training end time should not be later than 20: 30, and the online live training end time should not be later than 21: 00. Homework should not be arranged in any form such as pre-class preparation, after-class consolidation, homework practice, and WeChat group punching. The third is the "interruption" of the game, which requires local education departments to strengthen supervision with relevant departments in accordance with their management authority to ensure that no game services are provided to minors from 22: 00 to 8: 00 the next day.

　　Lv Yugang said that schools should have a sound homework management mechanism, and all subject groups should co-ordinate homework, so as to grasp a reasonable amount of homework and improve the quality of homework. Students should not be allowed to finish their homework during recess when they should go out for activities and jump around the playground, or during the lunch break. Schools and teachers should strengthen the guidance for students to complete their homework, especially to help students with learning difficulties, and increase the intensity of counseling and answering questions so that students can complete their homework within the specified time.

　　Lu Haifeng, director of the Education and Sports Bureau of Qidong City, Jiangsu Province, reminded schools to avoid the thinking mode of split thinking and binary opposition, and make efforts to properly handle several groups of relationships. The first is the relationship between "sleeping less" and "sleeping late" and "getting up early". According to the requirements of the Notice, schools should reasonably determine the schedule of work and rest, enhance the soft power in the publicity of work and rest, and enhance the hard power in the implementation of work and rest, and do not artificially require students to arrive at school in advance, and do not artificially occupy students’ school time. At the same time, they should be flexible and flexible in strictly implementing work and rest, for example, properly resettle individual students who arrive at school in advance due to special family circumstances; The second is the relationship between "less sleep" and "more homework" and "difficult homework". Schools should make great efforts in classroom research and win the light burden of schoolwork with the high efficiency of classroom; Pay attention to homework management and win the light load of homework with the high quality of design; The third is the relationship between "sleeping well" and "sleeping well" and "growing well". Schools should face students face to face, educate students to understand the importance of adequate sleep and develop good sleep habits. Heart-to-heart with parents to guide parents to be the guarantors of their children’s adequate sleep; Join hands with the society and participate in the governance of off-campus training institutions as much as possible to reduce the academic burden of students.

　　At the same time, Jiang Fan said that parents should take appropriate restrictions on children’s use of electronic products, and at the same time, they should set an example and consciously maintain a good work and rest, so that children can clearly understand the importance of sleep and develop a good habit of maintaining regular work and rest independently. Their team research shows that sacrificing sleep time for study can not bring about improvement in academic performance, but will cause extensive damage to executive function and affect the academic performance of children and adolescents. (Guangming Daily reporter Yan Xiaoyan)

　　Wu Zhongmei’s beauty lies not only in the green mountains and green waters, but also in the charm of food. Wuzhong people love to eat, but also eat, paying attention to "not eating from time to time", which is also regarded as the way to eat and drink in Soviet-style life. In good spring, this Wuzhong spring food picture book is for you. Go and have a good time!

　　Xiangchuntou

　　"Golden Cuisine" in Spring

　　Toona sinensis head is rich in nutrition and is the best among vegetables. Its most classic practice is scrambled eggs with Toona sinensis. In addition, it can also be pickled and made into Toona sinensis oil.

　　In Dongshan, Dongting, the local people blanch the Toona sinensis head and mix it directly with sesame oil. This is a very popular cold dish in Wuzhong restaurant.

　　Biluochun in water

　　Just as spring is blooming, the water shield of Taihu Lake, known as "Biluochun in Water", is quietly listed. Shepherd’s shield is a kind of jelly all over, which is very slippery, so it is difficult for ordinary people to catch it. Only an "old hand" can take it off with a stretch and a pinch. Because of this, there is a saying that "water shield is delicious but not easy to pick".

　　Water shield is rich in vitamins, amino acids, glucose, starch, protein and other nutrients, and has the effects of enriching blood, moistening lung, invigorating stomach and stopping diarrhea.

　　There are many ways to eat water shield. In Dongshan, Dongting, soup is the main favorite, such as water shield whitebait soup and water shield soup with thorn fish, so as to keep the purest water shield fresh.

　　Malan head

　　Delicious wild vegetables in they are tall once more in the spring wind

　　In the wild in spring, Malan heads are springing up from the ground like mushrooms after rain, which makes people drool.

　　Malantou is not only green and tender, but also has high nutritional value. Simply chop it, add salt and sugar, pour some sesame oil, press it in a small bowl and pour it on a plate. One spoon per person, a little taste, but not enough.

　　broad bean

　　Fresh and tender broad beans are cooked and eaten, but the meat taste can be forgotten.

　　In May, the broad beans are green and soft, and then melt, with a little salty fragrance and a little aftertaste, so tender that they can be eaten together with shells.

　　It can also be made into fennel broad beans, which has a crunchy taste. It is a snack that Suzhou people love to eat and a good appetizer.

　　snail

　　Old wine Mimi, snail Eee Eee

　　"Snails are meat no matter how small", not to mention "Qingming snails are better than geese"!

　　Snails have not been propagated before and after Qingming Festival. At this time, the meat quality is the most plump and the taste is the best. Whether it is spicy fried or soy sauce exploded, it is particularly delicious. Eat snails! This kind of spring is complete!

　　bamboo shoot soup with fresh and pickled streaky pork

　　The true meaning of "fresh" taste

　　Fresh salted meat and fresh meat are added with bamboo shoots and cooked into soup. Cured meat is generally cured in the twelfth lunar month, fresh meat must be pork belly of black-haired pig in Taihu Lake area, and bamboo shoots (also known as big bamboo shoots) should be fresh bamboo shoots in suburban forests and bamboo forests.

　　Shrimp with snail

　　A bud and a leaf come into the dish.

　　Biluochun in Dongting East and Xishan Mountain is fragrant, mellow in taste, green in soup color and slightly fruity. Shrimp with snail as a classic traditional dish has become a favorite spring delicacy of Suzhou people with its light, refreshing, delicious and attractive taste.

　　The pink shrimp and the emerald green Biluochun set each other off in an interesting way. It tastes both tender and delicious, and has the fragrance of tea. This wonderful combination of tea and vegetables has attracted countless diners.

　　Songhua tuanzi

　　Natural flavor from Shan Ye.

　　The pine flowers on the pine dumplings come from Pinus massoniana. When spring and summer alternate every year, the villagers in Wuzhong area go up the mountain to collect pine flowers, put them in bamboo plaques for drying, and then sieve the pine pollen with a sieve.

　　Made of glutinous rice flour with a ratio of six to four, wrapped in golden pine pollen, and steamed in a cage. The fillings are red beans, sesame seeds, Malan, etc., which are soft and glutinous, fragrant and unique.

　　Dafanggao

　　As the name suggests, cakes are "generous"

　　Dafang cake is square in appearance and white in color, which best represents the essence of Gusu cake, delicate and exquisite.

　　As thin as cicada’s skin is wrapped in stuffing, at first glance, you can see rose sauce and sugar mint rolling inside. Each face is printed with exquisite patterns, which makes people love it before they even take it.

　　Cauliflower pond bream

　　As stunning as rape blossoms.

　　When rape blossoms are in full bloom, it is the season when mud bream lays eggs. At this time, mud bream has the highest nutritional value. Suzhou people call this fish "cauliflower mud bream" alongside the stunning rape blossoms.

　　The water shield and pond slice, which is made of water shield and pond bream, a special product of Taihu Lake, is a soup in Su Bang’s famous dishes. The fish tastes smooth and delicious, and the soup is delicious and fragrant.

　　Sauce meat

　　"The first piece of meat in spring" must be eaten.

　　Square sauce meat is generally made of pork belly with suitable fat and thin, which is carefully pickled and cooked for several hours and then drenched with marinade.

　　The sauce meat that just came out of the pot is bright in color, with a ruddy and attractive luster. It tastes sweet but not greasy, crisp but not rotten, and melts in the mouth.

　　A red sauce meat with fresh green cauliflower is an indispensable delicacy in spring for Wuzhong people who are used to sweet and glutinous.

　　Jiuniang cake

　　The cake is not intoxicating, and everyone is intoxicated.

　　Su-style dim sum, which is seasonal in spring, takes the local winter wheat and distiller’s grains in Wuzhong as the main raw materials and only sells for one season.

　　It’s better to eat the cakes with hot food. When you take a bite, the skin is soft, sweet and sour, the taste is waxy, and there is the fragrance of the wine. Remember to eat while it’s hot!

　　The food is exquisite, with endless aftertaste. Look for seasonal food and taste this delicious spring. Which "taste" is good for you?

　　(Source: Wuzhong Publishing, Editor/Cheng Mengqing)

CCTV News:What you see in the picture is Chaka Salt Lake, which is the smallest of the four major salt lakes in Qaidam Basin, but its salt storage is the largest. When it is calm, Chaka Salt Lake is like a mirror, reflecting the distant snow-capped mountains and blue sky in the crystal clear lake, showing the natural scenery of "the lake is the same color as the sky, and the salt lake is the same as the snow peak".

In different seasons and at different times of the day, the scenery of Chaka Salt Lake is also ever-changing. In the past two years, Chaka Salt Lake has become a popular tourist punching place, and the number of tourists has continued to increase.

This is the Emerald Lake in Dachaidan Town, Haixi Prefecture. Because the lake water contains a large number of metallic elements such as magnesium, lithium and potassium and halides, the color of the lake water is either light blue or green or dark blue, and the lake water and salt flowers alternate, just like a piece of glittering and translucent jade, so it is called Jade Lake. Seen from the air, salt ponds of different sizes, shapes and shades are like gems scattered on the earth.

Because of its unique landscape, Emerald Lake is also a online celebrity punch-in point on the Chaidamu tourism ring road, which is called "the most beautiful emerald in the world" by tourists.

What we are seeing now is Yadan landform distributed in the northwest of Qaidam Basin. Yadan is a typical wind erosion landform, which means steep hills. Looking down from the sky, Yadan looks like ancient castles, and its formation has gone through about 700,000 to 300,000 years.

Yadan on the water brings out the best in each other with Yadan on the ground. Because of the crustal movement in Qaidam Basin, the lake water in Qinghai Lake and other places flows into Yadan territory through the underground, which forms the magnificent Yadan landscape on the water that we see before our eyes. Yadan on the water that stretches for 800 kilometers is spread all over the blue water, just like jasper on Gebi Beach and a quiet mirage.

What you see now is another famous salt lake in Qaidam Basin — — Chaerhan Salt Lake. It is not only the largest potash production base in China, but also one of the rare large inland salt lakes in the world, with more than 50 billion tons of sodium chloride stored in the lake.

The terrain around Chaerhan Salt Lake is flat, the whole lake seems to be a smooth mirror, and the clusters of salt flowers exposed on the water surface are like a series of beautiful collars. Looking from a distance, there is also a "Wanzhang Salt Bridge" floating on the brine in the salt lake. Tourists walk on the salt bridge, and the water and sky are the same, as if they were integrated into a beautiful landscape painting.