For thousands of years comets have been a mystery to man. They travel across the sky very fast and have a bright “tail” of burning gas. The comet Tempel 1 has an orbit（轨道） far outside the orbit of the furthest planet in our solar system, Pluto. It has been there for 4.6 billion years, 133 million kilometers from Earth. Last week a little American spacecraft crashed into Tempel 1. The spacecraft had a camera and it took a photograph of the comet every minute before it finally crashed into its surface.

    The space mission to Tempel 1 cost $335 million and was called Deep Impact. The spacecraft was travelling at 37,000 kilometers per hour when it hit the comet and the crash completely destroyed the spacecraft. But before it hit the comet, the spacecraft took some amazing photographs. The last one was a close-up picture which the spacecraft took just 3 seconds before it crashed into the comet.

    “Right now we have lost one spacecraft,” said a delighted NASA engineer. Deep Impact was like a American Independence Day fireworks display. It took many years to plan and ended in an enormous explosion. 

    The spacecraft which crashed into the comet was made of copper and was the size of a washing machine. It was dropped from a mothership into the path of the comet and the mothership then photographed the cloud of ice, dust and organic chemicals that rose from the surface of the comet after the crash.

    The crash completely destroyed the spacecraft but nothing really happened to the comet: experts believe that the crash slowed the comet down by no more than 1/10,000 of a millimeter a second.The aim of the mission was to study for the first time the interior of a comet.

    The mothership was 480 km from the explosion and observed the crash and the explosion with instruments for 800 seconds. Seven satellites, including the Hubble space telescope, watched the moment of drama, and over the next day and night about 50 telescopes on Earth were watching the distant comet.

    Let's have fun!

    Big Hugs Elmo

    Sesame Street Big Hugs Elmo. There are so many ways to play with Sesame Street Big Hugs Elmo! When preschoolers give Elmo a great big hug, he'll hug back, say fun phrases or sing a sweet song about hugs! Press Elmo's left foot and he will invite children to join in 1 of 4 imagination activities. There are 50 plus lively sounds and phrases. Elmo loves getting hugs from you. Let's play.

    Furby Boom Figure—Peacock

    A whole new generation of Furby creatures is about to be born! Dust off your Furbish dictionary and get ready to party with your Furby Boon creature! Your Furby has a mind of its own, and the way you treat your Furby will shape its personality—so the more fun you have with it, the better! It speaks more English the more you play with it. Tickle（挠痒）your Furby, talk to it, and feed it.

    FurReal Friends Cuddles My Giggly Monkey

    Cuddles My Giggly Monkey responds in lifelike ways to being loved and cared for. Feed her with the banana-shaped bottle and she will move her mouth like a real baby monkey, make slurping sounds, and even say “mm” when she's full! Snuggle（偎依）her close and she will turn to snuggle right back while making sweet, lovable monkey sounds. When it's time for bed, rock Cuddles, and she will also sleepy sounds.

    The First Flower Girl Doll—Disney Sofia

    Your little Sofia then first fan will love this target-exclusive 10 flower girl doll; she is inspired by the hit animated series from Disney Junior, Sofia the First. This beautiful Sofia doll is beautifully dressed in a never-before0seen gown inspired by the flower girl fashion she wore at her mom's royal wedding.

    I grew up in New York my whole life. I studied in a perfect college that happened only to be an hour away from home. Then, about three weeks before the spring term was over, my parents told me we were moving to Arizona that summer. They asked me if I was going to transfer (转学) to another college. I said no. I was not going to change everything in my life at one time and I loved my college and all the amazing things I was doing there. It was my second home; I would not leave everything I knew at the same time since that was asking for trouble.

    I never imagined it would be this hard but, at the same time, the best thing that could have happened to me.

    When out in Arizona, life was hard. I didn't know anyone other than my family and friends. I couldn't bear the extreme heat. But it has helped me so much. I have started working on my writing. I also have time to work out in the gym. It has helped me realize that no matter where you are or who you know you can always find something that you enjoy.

    When back at school in New York, it was hard as well. Living close to home was my security blanket. If something was wrong I could get in my car and drive home and see my family. After my family moved to another city, I lacked security and was always controlled by anxiety. However, it helped me learn independence and forced me to be brave.

    I' m so thankful that I didn't transfer to a different school, which has given me the opportunity to go back and see best friends in my hometown. A year ago, I officially left my hometown for good. It has helped me grow and I am so thankful that I have had this experience. Now, when I graduate from college, I can go anywhere I want. I am no longer afraid to go out on my own into the world. The world is full of opportunities and pleasure and I can't wait to see where I will be next.

    The national environmental watchdog has declared that boosting efforts to cut air pollution in northern China, especially winter smog from the burning of coal, is a mission for this year.

    Burning coal for winter heating has been listed as one of the primary causes of air pollution, Chen Jining, minister of environmental protection, said on Monday at the annual meeting on environmental protection in Beijing.“As much as 60 percent of smog content is caused by coal burning in the starting phase of each smog”, said Fang Li, an official with Beijing's Environmental Protection Bureau. Therefore, Beijing has declared that it will wipe out coal use in its most rural areas by 2020.

    To start with, Beijing will replace coal-fired heating stoves with those powered by electricity or gas in 400 villages this year, before taking the campaign to the districts of Chaoyang, Haidian, Fengtai and Shijingshan by 2017,said Guo Zihua, a municipal rural development official. Beijing's downtown districts of Dongcheng and Xicheng eliminated coal burning last year, officials said.

    The capital and other places in northern China experienced several smog alerts in November and December, when peak readings were many times higher than the national safety level. Obviously, the situation is deteriorating, and will become a norm. So the government came up with a “smog subsidy (津贴)” for those who work outdoors, and 95 percent of the respondents to a survey support it.

    The Trade Union in Zhengzhou City surveyed subscribers to its official WeChat account and found that 88 percent of nearly 400 respondents said priority should be given to outdoor workers on smoggy days But 9 percent said air pollution affects everyone so it would be unfair to only address the concerns of people who work outdoors.

    Over half of the respondents think the extra subsidy, if applied, could come in the form of protective tools or cash. Twenty-two percent said money is the easiest way. To finance the proposed subsidy, 53 percent think the government and companies should jointly pay the bill, while 44 percent said central and regional governments should be responsible.

D

With the completion of the Human Genome（基因组）Project more than 20 years ago, and the discovery of the double helix structure of DNA enjoying its 70th birthday last year, you might assume that we know how life works. Think again!

Evolution has a 4bn-year head start on us. However, several aspects of the standard picture of how life works-the idea of the genome as a blueprint, of genes as instructions for building an organism, of proteins as precisely tailored molecular（分子）machines and more-have wildly reduced the complexity of life. 

In the excellent book How Life Works, Philip Ball explorers the new biology, revealing life to be a far richer, more delicate affair than we have understood. Ball explains that life is a system of many levels-genes, proteins, cells, tissues, and body modules-each with its own rules and principles, so there is no unique place to look for an answer to it. 

Also, How Life Works is a much more appealing title than the overused question of "What is life?". We should be less concerned with what a thing is, and rather more focused on what a thing does. Defining a living thing implies an unchangeable ideal type, but this will run counter to the Darwinian principle that living things are four-dimensional, ever changing in time as well as space.

But it's an idea that is deeply rooted within our culture. Ball points out that we rely on metaphors（比喻）to explain and explore the complexities of life, but none suffice. We are taught that cells are machines, though no machine we have invented behaves like the simplest cell; that DNA is a code or a blueprint, though it is neither; that the brain is a computer, though no computer behaves like a brain at all.

Ball is a terrific writer, pumping out books on incredibly diverse subjects. There's a wealth of well-researched information in here, and some details that are a bit chewy for the lay reader. But the book serves as an essential introduction on our never-ending quest to understand life.