TWO NEW PLANETS FROM THE ANGLO-AUSTRALIAN PLANET SEARCH1
已发现四颗地球大小行星
天文学家又利用kepler发现两颗直径小于地球的行星。
这两颗行星围绕红巨星运行。
很可能是类木行星被红巨星蒸发，遗留下的致密核心形成的。
Astrophysicists have discovered two tiny, record-breaking planets that survived millions of years plowing through the broiling interior of a giant star.Outside our solar system, "these are the smallest planets ever found, they are the least massive, " said University of Montreal astrophysicist Gilles Fontaine, who co-authored the study with an international team led by four of his former Ph.D students.The planets KOI 55.01 and KOI 55.02 have radii about 0.76 and 0.87 times that of the Earth, the researchers reported online in the journal Nature Wednesday.That makes them slightly smaller than two planets billed by NASA earlier this week as the smallest ever found.The two planets circle a type of star known as a sub-dwarf that is much hotter than our sun and located 3,900 light years away from Earth, near the constellations Lyra and Cygnus."They are the hottest planets by a long shot because they are so close to their star," Fontaine said. The distance between the planets and their star is just 0.60 per cent and 0.76 per cent of the distance between the Earth and the sun."They have the shortest ever orbital period found for a planet," Fontaine added, noting that a "year" lasts just 5.8 hours for one of the planet and 8.2 hours for the other, shattering the previous known planetary record of 16 hours.Because they are so close to their star, they are "tidally locked" so that the same side always faces toward the star and the other side always faces away.Iron rainNaturally, the temperature on the star-facing side is extremely hot —around 8000 to 9000 C. That's hot enough to vapourize the iron that, along with nickel, make up most of the materials in the planets. In all likelihood, it forms clouds, drifts to the other side of planet, and rains back down in molten iron particles, Fontaine said.Kepler's planet-hunting methodNASA's Kepler telescope was designed to find planets outside our solar system by searching for planets that eclipse their stars, as seen from the telescope's vantage point. That is, the planets pass in front of and behind the star in the course of their orbit. As they pass in front of the star, they block part of the star, causing a dip in the amount of light detected by the telescope.The planets discovered by Fontaine and his collaborators do not eclipse their star —their orbits are tilted in such a way that Kepler never sees them cross in front of the star. However, the researchers used a new method that also relies on small changes in the brightness of light detected by the telescope."If hell exists, it has to be on these two planets."The sub-dwarf is believed to have shrunk down just 18 million years ago from being a massive red giant – a star so big that the planets would have found themselves deep inside the star's envelope.Elizabeth "Betsy" Green, an associate astronomer at the University of Arizona's Steward Observatory, who co-authored the research, said the two planets were likely originally giant planets like Jupiter that were closer to their star than Jupiter and further out than Earth is from our sun.Their star would have originally have be sun-like, but as it ran out of fuel, it would have expanded 100 times in size to spend the next one to five million years as a red giant, engulfing the planets at some point.The millions of years they spent plowing through the star's broiling atmosphere would have taken their toll. The friction would have slowed the orbiting planets down, causing them to spiral closer to the centre of the star. It would have stripped off the gaseous and liquid outer layers of the planet, leaving just their small, solid cores.At the same time, the friction from the planets likely helped strip the atmosphere off the star, leaving behind just the star's core in the form of a sub-dwarf star, which has a lifetime of about 100 million years."We think this is the first documented case of planets influencing a star's evolution," said Stephane Charpinet, an astronomer at the Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse-CNRS, in France who led the research, in a statement.It is also one of only three known cases of planets surviving immersion inside a star.Accidental discoveryThe team discovered the two planets by accident during a study of pulsating stars using NASA's Kepler space telescope. Pulsating stars expand and contract rhythmically due to pressure and gravitational forces, and studying the pulsations — a field of research known as astroseismology — can provide information about their mass, temperature, size and sometimes their interior structure.Our sun as a red giant?Our sun, powered by the fusion of hydrogen into helium, is expected to start running out of fuel in around five billion years. At that point, it will expand into a red giant, 100 times its current size. That will cause it to engulf its three nearest planets, Mercury, Venus and Earth.The pulsations of the sub-dwarf were analyzed by Charpinet and Fontaine using computer models. In the process, the researchers noticed the star flickering faintly every 5.76 and 8.23 hours.Eventually, they figured out what caused the flickering — two planets circling the star, reflecting different amounts of light as they move through different positions, as the moon does while orbiting the Earth."You will have a new planet, a full planet, a first quarter, a last quarter," Fontaine said. That results in light variations of just 50 parts per million, but enough to detect using the Kepler telescope's sensitive photometer.This is the first time new planets have ever been discovered using this technique.Based on the information gathered about the star using astroseismology, the researchers were able to figure out the size, mass, temperature and other information about the planets.。
bbc英语听力练习：新行星中的外星球
bbc英语听力练习：新行星中的外星球Eight new planets 新行星中的“外星球”天文学家说在遥远的太阳系外最新发现的八颗新行星中的一颗是“最类似地球的外星球”。
这八颗类地行星是由美国国家航空航天局（NASA）的开普勒太空望远镜所探测出的。
此探测结果是在美国天文学会的一次会议上公布的。
以下是 BBC 记者 Jonathan Webb 的报道：Spotting ‘Alien Earths’ is the reason the Kepler spacecraft was launched six years ago. It looks deep into space for tell-tale dips in the brightness of faraway stars.Eight new so-called exoplanets were revealed here, taking Kepler’s overall tally1 to more than 1,000. But only veryfew planets from that total are thought to be Earth-like and habitable, sitting in a temperate2 Goldilocks zone aroundtheir various suns.One of the new arrivals, called Kepler 438b, is the most like our home that astronomers3 have ever seen： just 12% bigger than Earth and 40% warmer.They say if we could stand on its surface, nearly 500light years away, the sky would be red because of the dwarf4 star it has for a sun.Glossary 词汇表tell-tale泄露内情的faraway遥远的exoplanet外星球tally累计数字，总数habitable可居住的Goldilocks zone适居带light years光年dwarf star点击收听单词发音收听单词发音1 tally Gg1yqn.计数器，记分，一致，测量；vt.计算，记录，使一致；vi.计算，记分，一致参考例句：Don't forget to keep a careful tally of what you spend.别忘了仔细记下你的开支账目。
高一英语宇宙探索单选题50题
高一英语宇宙探索单选题50题1. The _____ is a large system of stars, gas, and dust held together by gravity.A. planetB. galaxyC. moonD. comet答案：B。
本题考查宇宙探索中的基本词汇。
选项A“planet”（行星）是围绕恒星运行的天体，与题意不符；选项B“galaxy”（ 星系）是由恒星、气体和尘埃组成的巨大系统，由引力维系在一起，符合描述；选项C“moon”（ 月亮）是地球的卫星，只是一个小天体，不是这种大规模的系统；选项D“comet”（ 彗星）是一种特殊的天体，与星系的概念不同。
2. Scientists believe the universe _____ from a big bang.A. was originatedB. originatedC. has been originatedD. had originated答案：B。
本题考查宇宙起源相关的表达以及动词的用法。
“originate”表示“起源”，在这里是不及物动词，没有被动形式，所以选项A、C错误；选项D“had originated”是过去完成时，表示过去的过去，这里没有这种时间上的先后关系；选项B“originated”使用一般过去时，表达科学家认为宇宙起源于大爆炸这个过去的事实。
3. Which of the following is not a planet in our solar system?A. VenusB. SiriusC. MarsD. Jupiter答案：B。
本题考查太阳系中的行星知识和词汇。
选项A“Venus” 金星）、选项C“Mars” 火星）、选项D“ Jupiter” 木星）都是太阳系中的行星；而选项B“Sirius”（ 天狼星）是夜空中最亮的恒星，不是太阳系中的行星。
4. The sun is at the center of our _____.A. galaxyB. solar systemC. universeD. constellation答案：B。
用英语介绍中国宇航员作文六年级
用英语介绍中国宇航员作文六年级全文共6篇示例，供读者参考篇1Soaring Into Space: The Remarkable Journey of China's AstronautsHave you ever dreamed of traveling to space? I know I have! The vast expanse of the cosmos, filled with twinkling stars and mysterious planets, has always captivated my imagination. And you know what's even more exciting? China has been making incredible strides in space exploration, with brave astronauts venturing into the unknown and pushing the boundaries of human achievement.Let me tell you about some of these incredible men and women who have become true heroes in my eyes. They are the ones who have risked everything to explore the final frontier, paving the way for future generations to experience the wonders of space travel.One of the most famous Chinese astronauts is Yang Liwei. In 2003, he made history by becoming the first Chinese citizen to travel into space aboard the Shenzhou 5 spacecraft. Imagine theexcitement and anticipation he must have felt as the rocket engines roared to life, propelling him into the vast unknown! For nearly 21 hours, Yang orbited the Earth, conducting scientific experiments and capturing breathtaking views of our planet from above.But Yang Liwei is just the beginning. Since then, China has sent numerous other astronauts into space, each one adding to the nation's growing expertise and accomplishments in space exploration.Take, for instance, Zhai Zhigang, who became the first Chinese astronaut to conduct a spacewalk in 2008. Clad in a bulky spacesuit, he stepped out of the Shenzhou 7 spacecraft and into the vacuum of space, a feat that requires immense courage and skill. Can you imagine the sense of wonder and awe he must have felt as he gazed upon the Earth from that unique vantage point?Another remarkable astronaut is Liu Yang, who made history in 2012 as the first Chinese woman to travel to space. Her mission aboard the Shenzhou 9 spacecraft not only inspired countless young girls like me to pursue their dreams but also showcased China's commitment to gender equality in its space program.And let's not forget about the incredible team of astronauts who have lived and worked aboard China's Tiangong space stations. These orbiting laboratories have served as home away from home for many Chinese astronauts, allowing them to conduct cutting-edge research and experiments in the unique environment of microgravity.One of the most recent and exciting developments in China's space program is the construction of the Tiangong Space Station. This massive orbiting outpost, weighing over 100 tons, is a testament to China's ambitions and technological prowess. Imagine being one of the astronauts living and working aboard this state-of-the-art facility, conducting groundbreaking experiments and gazing down at our beautiful planet from their unique vantage point.But being an astronaut isn't just about the thrill of space travel; it's also about dedication, hard work, and perseverance. These men and women have undergone rigorous training, both physical and mental, to prepare themselves for the challenges of space exploration. From simulating weightlessness in underwater training facilities to mastering complex scientific concepts, their journey to becoming astronauts has been nothing short of remarkable.And let's not forget the unsung heroes behind the scenes –the engineers, scientists, and mission control teams who work tirelessly to ensure the success of each and every space mission. Their expertise and dedication are what make these incredible feats of human exploration possible.As I look to the future, I can't help but feel excited about the possibilities that lie ahead for China's space program. Who knows, maybe one day I'll be among the next generation of Chinese astronauts, following in the footsteps of these trailblazers and embarking on my own journey to the stars.But for now, I'm content to learn about these incredible men and women, to be inspired by their courage and determination, and to dream of the day when I, too, might have the chance to gaze upon our beautiful planet from the vast expanse of space.So, let's give a round of applause to China's astronauts – the pioneers who have dared to venture where few have gone before, inspiring us all with their passion for exploration and their unwavering spirit of adventure.篇2China's Taikonauts - Brave Explorers of SpaceHave you ever dreamed of traveling to space and walking on the moon? Looking up at the twinkling stars and planets in the night sky fills me with wonder about the vast universe beyond our planet Earth. China has some incredibly brave men and women called taikonauts who have traveled into outer space aboard spacecraft to conduct scientific experiments and even live on board orbiting space stations! Let me tell you more about these space explorers from my country.The very first Chinese person in space was Yang Liwei in 2003. He flew aboard the Shenzhou 5 spacecraft and spent nearly 22 hours orbiting the Earth. Yang was a fighter pilot in the People's Liberation Army Air Force before being selected to be part of China's taikonaut program in 1998. During his historic flight, he circled the globe 14 times before safely returning to Earth. Yang became a national hero celebrated across China for his pioneering mission into the cosmos.Following Yang's success, China sent two more taikonaut crews into space over the next two years. The two-man crew of Shenzhou 6 in 2005 included Fei Junlong and Nie Haisheng, who carried out scientific experiments during their nearly 5 days in orbit. Then in 2008, Zhai Zhigang conducted China's first everspacewalk on the Shenzhou 7 mission, exiting the spacecraft while still in orbit to test spacesuit operations.However, one of the biggest accomplishments for China in space exploration was the launching of the Tiangong space stations beginning in 2011. Tiangong-1 was an early prototype station to allow taikonauts to practice operations for future permanent space stations. Two crews visited Tiangong-1 in 2012 and 2013 for short-term stays.The real prize was the much larger Tiangong-2 space station that was launched in 2016. Two crews of taikonauts lived on board Tiangong-2 for monthly-long residencies, setting new records for the longest Chinese space missions. The first Tiangong-2 crew included Jing Haipeng, who had previously visited Tiangong-1, and Chen Dong. They spent a full month aboard the space station conducting scientific experiments and testing systems.The second crew of Tiangong-2 had an amazing mission in late 2016 and early 2017. It included China's first female taikonaut in space - Wang Yaping! Along with her crewmates Jing Haipeng (returning for his third mission) and Chen Dong, she participated in over 300 scientific experiments during their month in orbit.One of the most exciting parts of their mission was when Wang Yaping gave a live video lesson from space that was broadcast to over 60 million students across China! She demonstrated how objects move differently in microgravity conditions and conducted experiments with simple things like a spinning top and water globes. This inspiring educational experience sparked huge excitement about space among Chinese children like myself.Most recently, in late 2021, China achieved another major milestone by launching the first module of篇3The Courage and Determination of Chinese AstronautsHave you ever dreamed of traveling to space and exploring the vast unknown of the universe? Well, for the brave men and women who become astronauts, that dream becomes a reality! In China, we have an impressive team of astronauts who have ventured beyond Earth's atmosphere on many important space missions. Let me tell you about some of these courageous space explorers.One of the most famous Chinese astronauts is Yang Liwei. In 2003, he made history by becoming the first Chinese citizen totravel to space aboard the Shenzhou 5 spacecraft. Can you imagine how incredibly exciting but also terrifying that must have been? Yang had to go through years of intense training to prepare his body and mind for the challenges of spaceflight. During his 21-hour journey orbiting the Earth, he conducted scientific experiments and even had a video conversation with leaders in China from space! Yang's pioneering mission paved the way for future Chinese space exploration.Another accomplished astronaut is Zhai Zhigang. In 2008, he became the first Chinese astronaut to conduct a spacewalk, an extremely dangerous undertaking where you have to leave the safety of the spacecraft while equipped with just a pressurized spacesuit. Zhai spent about 20 minutes outside the Shenzhou 7 craft, waving to cameras and delivering a touching message about the importance of pursuing your dreams with perseverance. His brave extravehicular activity (the official name for a spacewalk) marked a huge milestone for China's fledgling space program.The first Chinese woman in space was Liu Yang in 2012. For many days, she and her crew operated the Shenzhou 9 craft while it was docked at the orbiting Tiangong-1 space module. Liu conducted experiments, gave a video lecture to students onEarth, and even found time for a space-based hair trimming session! Her participation was an inspiration for many young girls in China who dream of one day leaving Earth's atmosphere themselves.In 2013, Wang Yaping became the second Chinese woman to fly in space when she traveled aboard Shenzhou 10. But she wasn't just along for the ride – during this mission, Wang gave an incredible physics lesson that was broadcasted live to over 60 million students across China! Using physics demonstrations to explain concepts like inertia and gravity, Wang made study of these topics fun and engaging from her unique classroom orbiting hundreds of miles above the planet.More recently in 2021, the crew of the Shenzhou 13 mission spent an incredible 6 months living and working aboard China's new Tiangong space station. The three astronauts - Zhai Zhigang, Ye Guangfu, and Wang Yaping - conducted dozens of scientific experiments, multiple spacewalks to upgrade station components, and videos calls with students down on Earth. They set a new record for the longest single spaceflight by Chinese astronauts.These are just a few examples of the brave and accomplished astronauts who have represented China in spaceover the past couple of decades. Becoming an astronaut takes incredible courage, years of challenging training, and an unwavering commitment to explore the great frontier beyond our planet. But for those select few who achieve this massive goal, their contributions to space exploration and scientific discovery are inspiring for all of us.China's space program will continue sending robotic probes and human crews deeper and deeper into space in the years ahead. The Tiangong space station is just the first step - perhaps one day we will have Chinese astronauts walking on the surface of the Moon or even Mars! Those future explorers will be following in the incredible footsteps of trailblazers like Yang Liwei, Zhai Zhigang, Liu Yang, Wang Yaping and so many other heroes.The endeavors of China's astronaut corps teach all of us students valuable lessons. We learn first-hand the importance of working hard to achieve our biggest dreams. We see how vital science, math and physics are for advancing humanity's knowledge and capabilities. And we witness the amazing things that are possible when we refuse to give up in the face of challenges, no matter how daunting they seem at first.So the next time you look up at the night sky sparkling with stars, remember the courageousChinese astronauts who have traveled amongst those distant lights. They took the path of most resistance, the harder road, in pursuit of exploration and discovery. Thanks to their sacrifice and determination, all of our horizons have expanded in wondrous new ways. If you too have a dream of venturing where few have gone before, let the achievements of China's space pioneers inspire you to reach for the stars!篇4Chinese Astronauts: Exploring the Final FrontierHave you ever looked up at the night sky and wondered what it would be like to travel to space? To float weightlessly among the stars and gaze back at our beautiful blue planet Earth from above? For me and many of my friends, becoming an astronaut is one of our biggest dreams!Did you know that China has its own astronauts who have traveled to space? They are called taikonauts, a combination of the Mandarin word for space (taikong) and the Greek word for sailor (nautes). Pretty cool, right? Let me tell you all about theexciting history of Chinese space exploration and the brave taikonauts who have ventured into the unknown.China's first steps into spaceChina's journey into space began in the 1950s when scientists started researching rockets and satellites. In 1970, China successfully launched its first satellite called Dong Fang Hong 1. This was a huge milestone and paved the way for future space missions.After this early success, work began on sending humans into space. In the 1990s, China started selecting potential astronaut candidates from the air force. They went through incredibly tough physical and mental training to prepare for the challenges of spaceflight.On October 15, 2003, the momentous day finally arrived. Yang Liwei, a 38-year-old fighter pilot, blasted off aboard the Shenzhou 5 spacecraft. He orbited the Earth 14 times over 21 hours, becoming China's first taikonaut in space! The whole country celebrated this historic achievement with pride.More taikonaut missions followed in the coming years as China accelerated its space program. In 2008, Zhai Zhigang became the first Chinese astronaut to perform a spacewalk. In2012, Liu Yang became the first Chinese woman in space aboard the Shenzhou 9 mission. And in 2013, Wang Yaping gave a videocall lecture from space to over 60 million students across China!The Chinese space stationOne of China's greatest space accomplishments so far has been the construction of its own space station called Tiangong (which means "Heavenly Palace"). It consists of multiple modules launched and assembled in orbit.The core module of Tiangong, called Tianhe, was launched in 2021. Over the next two years, additional science modules were sent up and docked with Tianhe one by one. Sophisticated robotic arms were used to carefully connect all the different pieces together.In late 2022, after all the modules were linked up, Tiangong was finally completed and ready for astronauts to live and work aboard. A three-person crew called the Shenzhou 15 mission was the first to take up residence for an extended stay.Living and working on TiangongSo what's it like for the taikonauts living aboard China's new space station? Well, it's definitely not easy! They have to adjustto living in microgravity where everything floats around. Simple tasks like eating, drinking and using the bathroom become much trickier when you're weightless.The crew spends a lot of their time conducting scientific experiments in areas like biology, physics, astronomy and more. The unique space environment allows them to study things you can't recreate on Earth. They also have to exercise regularly using special equipment so their muscles and bones don't get weak from the lack of gravity.Occasionally, they'll get a brief chance to look out the window and soak in the breathtaking views of Earth below. They say seeing our gorgeous planet hanging in the blackness of space is an experience that never gets old.Every few months, a new crew arrives at Tiangong to take over from the previous one through a choreographed "handover" process. RoboticShenzhou and Tianzhou cargo vehicles also periodically dock to deliver fresh supplies and experimental payloads.What's next for China in space?China has many more exciting space goals lined up over the next decade. This includes collecting samples from asteroids andthe Moon, building an advanced space telescope, and even exploring Mars by landing rovers and hopefully one day humans!With its rapidly growing capabilities, China is positioning itself as a major player in space alongside other pioneering nations like the U.S. and Russia. The spirit of exploration and curiosity burns brightly in the hearts of Chinese taikonauts and space engineers.Who knows? Maybe someday I or one of my classmates could be among the next generation to carry on China's space adventures. We'll continue reaching for the stars and unveiling the many mysteries that the final frontier still holds. The future of space travel is looking brighter than ever!篇5Chinese Astronauts: Exploring the Mysteries of SpaceHave you ever looked up at the night sky and wondered what it would be like to float among the stars? Well, some brave men and women from China have actually experienced that amazing feeling! They are called astronauts, and their job is to travel into outer space and explore the great unknown.China's first astronaut was Yang Liwei, who blasted off in 2003 aboard the Shenzhou 5 spacecraft. He orbited the Earth 14 times during his historic 21-hour journey, becoming a national hero. Just imagine how excited he must have felt as the powerful rocket engines fired and propelled him beyond our planet's atmosphere! Seeing the curved horizon of the Earth from space is something most of us can only dream about.Since Yang's pioneering flight, many more Chinese astronauts (called yuhangyuans in Mandarin) have followed in his footsteps. In 2012, Liu Yang became the first Chinese woman in space when she flew on the Shenzhou 9 mission. Having both male and female astronauts shows that China values equality and recognizes talent in everyone.Another major milestone was the launch of China's Tiangong space stations. Tiangong-1 was a small prototype station, but Tiangong-2 was much larger and allowed astronauts to live and work in space for longer periods. Learning how to live in microgravity and conduct science experiments in orbit helps prepare for even more ambitious future missions.The crown jewel of China's space program so far is the Tiangong space station, a genuine orbital laboratory about the size of a football field. Multiple astronaut crews have livedaboard Tiangong since 2021, conducting hundreds of scientific studies. Living in space is extremely challenging, but the astronauts are tough and highly trained to handle any difficulties that arise.Some of the experiments on Tiangong have looked at how plants grow in space, which is important for long space journeys where astronauts need to grow their own food. Other studies have investigated new advanced materials and watched how flames behave in microgravity. The astronauts have also had fun testing out flying objects like spinning tops and gyroscopes in weightlessness!But being an astronaut isn't all fun and games – it's also an immense amount of hard work. The astronauts have to exercise for hours every day so their muscles and bones don't get weak from the lack of gravity's effects. They also have to be prepared for emergencies like electrical failures, computer glitches, or even getting hit by tiny bits of space junk flying at extreme speeds.As amazing as the Tiangong station is, it is just the first step towards China's ultimate goal of sending astronauts to the Moon and eventually even Mars! In the coming decades, we may seethe first Chinese "yuhangyuan" leave their bootprints on alien worlds. How incredible is that?While space travel is filled with challenges, the bravery and determination of China's astronauts is篇6Title: The Brave Chinese Astronauts Reaching for the StarsHave you ever looked up at the night sky and wondered what it would be like to travel into space? Well, let me tell you about the amazing Chinese astronauts who have made that dream a reality!China has a long and fascinating history in space exploration. Did you know that one of the first rockets in China was invented way back in the 13th century? It was called the 'fire arrow,' and it was used for military purposes. Isn't that cool?Fast forward to the 21st century, and China has become a major player in space exploration. In 2003, China sent its first astronaut, Yang Liwei, into space aboard the Shenzhou 5 spacecraft. He orbited the Earth 14 times and became a national hero!Since then, China has launched several crewed missions into space, each one more impressive than the last. In 2008, the Shenzhou 7 mission included China's first-ever spacewalk, performed by astronauts Zhai Zhigang and Liu Boming. Can you imagine floating outside the spacecraft, looking down at the Earth from outer space? It must have been an incredible experience!But that's not all! China has also been busy building its own space station, called Tiangong (which means "Heavenly Palace"). In 2021, the core module of the Tiangong space station was launched into orbit, and since then, several crewed missions have visited the station to conduct various experiments and research.One of the most recent and exciting missions was the Shenzhou 14 mission, which launched in June 2022. Three astronauts – Chen Dong, Liu Yang, and Cai Xuzhe – spent six months living and working on the Tiangong space station. During their stay, they carried out numerous scientific experiments and even conducted a spacewalk to test new technology.Liu Yang, by the way, is a true pioneer. She was the first Chinese woman to travel to space when she participated in the Shenzhou 9 mission in 2012. Isn't that amazing? Womenastronauts like her are inspiring young girls everywhere to pursue their dreams in science and exploration.One thing that makes Chinese astronauts so special is their dedication and hard work. Becoming an astronaut in China is no easy feat. Candidates go through rigorous training programs that test their physical and mental abilities to the limit. They have to learn how to operate complex machinery, conduct scientific experiments, and even survive in case of emergencies.But the astronauts don't just train on Earth – they also have to prepare for the challenges of living and working in space. This includes learning how to handle the effects of microgravity, such as muscle atrophy and bone loss. They also have to practice spacewalks in special underwater training facilities that simulate the conditions of outer space.When I grow up, I dream of becoming an astronaut myself. I want to experience the thrill of blasting off into space, seeing the Earth from a whole new perspective, and contributing to humanity's understanding of the universe. And who knows? Maybe one day, I'll even get to visit the Chinese space station or go on a mission to the Moon or Mars!For now, though, I'll keep following the adventures of Chinese astronauts with great enthusiasm. They are true heroes,pushing the boundaries of human exploration and bringing us one step closer to the stars. Their bravery, determination, and commitment to science are truly inspiring.So the next time you gaze up at the night sky, remember the incredible men and women who have ventured into the unknown, representing China's space program with pride. They are living proof that with hard work and perseverance, anything is possible – even traveling to the farthest reaches of the cosmos!。
三年级英语太空旅行单选题30题
三年级英语太空旅行单选题30题1. There are many planets in the space. Which one is the biggest?A. EarthB. MarsC. JupiterD. Venus答案：C。
Jupiter（ 木星）是太阳系中最大的行星，Earth（ 地球）是我们居住的星球，但不是最大的；Mars 火星）比地球小；Venus 金星）也比木星小。
2. We can travel to space by ______.A. carB. planeC. spaceshipD. train答案：C。
Spaceship（宇宙飞船）是能够带我们去太空旅行的工具，car（汽车）、plane（飞机）、train（火车）都不能在太空中行驶。
3. The sun is a ______.A. planetB. starC. moonD. comet答案：B。
The sun（太阳）是一颗恒星（star），planet（行星）是围绕恒星运行的天体，moon 月亮）是地球的卫星，comet 彗星）是一种特殊的天体。
4. Which is not a planet?A. MercuryB. MoonC. SaturnD. Uranus答案：B。
Moon（ 月亮）是地球的卫星，不是行星。
Mercury（ 水星）、Saturn 土星）、Uranus 天王星）都是行星。
5. In space, we can see many ______.A. birdsB. starsC. flowersD. trees答案：B。
在太空中，我们能看到许多星星（stars），birds（ 鸟）、flowers 花）、trees 树）都不能在太空中存在。
6. There are many ______ in the space.A. starsB. carsC. catsD. dogs答案：A。
本题考查太空里常见的事物。
Two_new_planets_called“superEarth”_两颗“超级地球”新行星
疯狂英语（新读写）一个国际科研团队发现了两颗距离地球仅100光年的新行星，其中一颗可能适合生命生存。
主题语境：太空探索篇幅：304词建议用时：6分钟Two new planets called “super Earth ”两颗“超级地球”新行星四川仲开蓉1An international team of scientists says it has discovered two new “superEarth ”type planets about 100light years away,one of which may be suitable for life.Unlike any of the planets in our solar system,the nearly 1,600known superEarths are larger than Earth,but lighter than icy planets like Uranus and Neptune.2Researchers at Belgium s University of Liège announced that they found another one while using Earthbased telescopes toconfirm the existence of a differentplanet initially discovered by a NASA satellite in the same solar system.3NASA s satellite found planet LP 8909b,which is about 30%larger than Earth and orbits its sun in just 2.7days.Researchers at the University of Liège used their telescopes in Chile and Spain to take a closer look at the planet with highprecision cameras.That s when the scientists discovered another planet,LP 8909c (renamed SPECULOOS2c by researchers at the University of Liège),which is 40%larger than Earth and takes 8.5days to orbit itssun.39Crazy English 2023.64Francisco Pozuelos,a researcher at the Institute of Astrophysics of Andalusia and one of the main coauthors of the paper,said in a news release that the planet could be suitable for life despite being a mere 3.7million miles from its sun.Earth,by comparison,is located over 93million miles away from our sun.“Although this planet orbits very close to its star,at a distance about 10times shorter than that of Mercury around our Sun,the amount of stellar irradiation (恒星辐射量)it receives is still low,and could allow the presence of liquid water on the planet s surface,provided it has a sufficient atmosphere,”Pozuelos said.“This is because the star LP 8909c is about 6.5times smaller than the Sun and has a surface temperature half that of our star.”5Scientists at the University of Liège then follow up NASA s findings with groundbased telescopes to confirm and characterize the planets.ReadingCheckDetail 1.Which of the following is the smallest?A.The Sun.B.The Earth.C.LP 8909b.D.LP 8909c.Detail 2.How did scientists discover LP 8909c?A.By analyzing Earth s orbit.B.By taking LP 8909b s photos.C.By comparing with LP 8909b.D.By using groundbased telescopes.Gist 3.What s talked about in paragraph 4?A.Different opinions about the new planet.B.Scientists future plan on the new planet.C.Reasons for the new planet suitable to live parisons between LP 8909c and ourEarth.40疯狂英语（新读写）Inference 4.What s the purpose of the text?A.To prove great breakthroughs made by scientists.B.To show two newly discovered superEarths.C.To tell us LP 8909c is the future substitute of our Earth.D.To talk about two newlyfound planets suitable for life.LanguageStudyⅠ.Difficult sentence in the text“Although this planet orbits very close to its star,at a distance about 10times shorter than that of Mercury around our Sun,the amount of stellar irradiation it receives is still low,and could allow the presence of liquid water on the planet s surface,provided it has a sufficient atmosphere,”Pozuelos said.皮苏埃洛斯说：“尽管这颗行星的轨道非常靠近它的恒星，且与其恒星的距离只有水星与太阳间距离的1/10左右，但它接收到的恒星辐射量仍然很低。
UNIT1 SCIENCE AND SCIENTISTS高二英语(人教版2019选择性必修第二册)
Read Passage 2 and finish the table.
Review the content
①描述科学家(Para. 1)
②描述科学家成就(Para. 2)
Stephen Hawking was one of the most famous and gifted
scientists in physics.
point in time and space.
④描述科学精神的意义
The story of Hawking
③描述科学家成就(Para. 3)
Linking words: in general, the first, the other, besides, furthermore, above all
何事 （what）
何人 （who）
为何 （why）
何时 （when）
何地 （where）
如何 （how）
WhaWAtehriaomtspipmaocpreot”ra?tnanttppeerrssoonnaalitlyitaynadnqduaqlituieasliintiQesiainnXuQeisahnenXhueelpsehdehnimheealrpnetdhehniammeeaofr“nthe Father of China’s the name of “the Father of China’s Aerospace”?
went to the United States to pursue his graduate studies
helped conduct important research into rocket propulsion founded the Jet Propulsion Laboratory with several other people returned to China;developed China’s rocket science and its space and missile programme launched China’s first man-made satellite
上海市浦东新区2021届高三上学期一模英语试题含解析
18. A. His flight number and arrival time.
B. The cause of the flight's late arrival.
C. The number of his luggage check.
D. It can create smells and give them off to any scene.
15. A. It helps shoppers locate the right brand of perfume.
B. It helps shoppers check out the perfumes before they buy.
阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。
Since astronomers confirmed the presence of planets beyond our solar system, called exoplanets, humans_________1_________(wonder) how many could harbor life.
Our galaxy holds at least an______4______(estimate) 300 million of these potentially habitable worlds, based on even the most conservative interpretation of the results in a new study to be published in The Astronomical Journal.
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T HE A STROPHYSICAL J OURNAL,555:410È417,2001July1(2001.The American Astronomical Society.All rights reserved.Printed in U.S.A.TWO NEW PLANETS FROM THE ANGLO-AUSTRALIAN PLANET SEARCH1 R.P AUL B UTLER,2,3C.G.T INNEY,3G EOFFREY W.M ARCY,4H UGH R.A.J ONES,5A LAN J.P ENNY,6AND K EVIN A PPS7Received2000December25;accepted2001March7ABSTRACTPrecise Doppler measurements from the Anglo-Australian Telescope(AAT)UCLES spectrometerreveal periodic Keplerian velocity variations in the stars HD160691and HD27442.HD160691has aperiod of743days,a semiamplitude of54m s~1,and a high eccentricity,e\0.62,typical of extrasolarplanets orbiting beyond0.2AU.The minimum(M sin i)mass of the companion is1.97and theM J, semimajor axis is1.65AU.HD27442has a415day period,a semiamplitude of32m s~1,and an eccen-tricity of0.058.The minimum mass is1.43and the semimajor axis is1.18AU.This is theÐrstM J,extrasolar planet orbiting beyond0.2AU that is in a circular orbit similar to solar system planets.Thephoton-limited precision of AAT/UCLES measurements is3m s~1as demonstrated by stable stars andKeplerianÐts to planet-bearing stars.In addition,we present conÐrmation of four previously announcedplanets.Subject headings:planetary systemsÈstars:individual(HD160691,HD27442)1.INTRODUCTIONAll D50extrasolar planets discovered over the last5yr have come from precision Doppler surveys of nearby dwarf stars ranging in spectral type from late F through M4 (Mayor&Queloz1995;Marcy&Butler1998,2000;Noyes et al.1997;Cochran et al.1997;Vogt et al.2000;Kurster et al.2000;Udry et al.2000;Fischer et al.2001).With one exception(Marcy,Butler,&Vogt2000),all the published planets have Doppler velocity amplitudes greater than30m s~1.With a measurement error of D10m s~1,Doppler velocity amplitudes of30m s~1are the smallest that can be easily detected.Detection of planets with smaller ampli-tudes,such as solar system analogs and Neptune-to-Saturn mass planets in short period orbits,requires measurement precision of3m s~1or better(Butler&Marcy1997;Butler et al.2001).For the case of massive planets orbiting within3AU,the D50known planets constitute a useful statistical sample. The substellar companion mass function abruptly rises at 5and continues to rise down to the detection limit near M J1About7%of nearby stars have massive planets with M J.orbital periods less than5yr,including D0.75%with““51 PegÈlikeÏÏplanets in3È5day circular orbits(Cumming, Marcy,&Butler1999;Butler et al.2001).Although existing planet hunting techniques are still in their infancy,two primary results have emerged over the last5yr.Extrasolar planets are common,and the architecture of planetary1Based on observations obtained at the Anglo-Australian Telescope, Siding Spring,Australia.2Department of Terrestrial Magnetism,Carnegie Institution of Wash-ington,5241Broad Branch Road,NW,Washington,DC20015-1305; paul=.3Anglo-Australian Observatory,P.O.Box296,Epping,NSW1710, Australia.4Department of Astronomy,University of California,Berkeley,CA 94720;and Department of Physics and Astronomy,San Francisco State University,San Francisco,CA94132.5Astrophysics Research Institute,Liverpool John Moores University, Twelve Quays House,Egerton Wharf,Birkenhead CH411LD,UK.6Rutherford Appleton Laboratory,Chilton,Didcot,Oxon OX110QX, UK.7Physics and Astronomy,University of Sussex,Falmer,Brighton BN1 9QJ,UK.systems is richer and more complicated than previously imagined.Future breakthroughs will require greater measurement sensitivity.In particular,the most pressing questions at the moment are does the planet mass function continue to rise through the Jupiter to the Neptune-mass range,and what fraction of stars have““solar systemÈlikeÏÏplanets,i.e., Jupiter and Saturn analogs in circular orbits beyond4AU?Doppler precision of3m s~1or better is required to address these questions.The Anglo-Australian Planet Search,therefore,has the speciÐc goal of achieving a long-term precision of3m s~1.In°2we show that this goal has been reached.Section3 reports the stellar characteristics and Doppler velocities of the host stars for two giant planets that have emerged from this survey.Section4presents velocities and orbital solu-tions from the Anglo-Australian Telescope(AAT)data for four planets previously announced from the Keck, CORALIE,and ESO planet surveys and is followed by a discussion of our results.2.THE ANGLO-AUSTRALIAN DOPPLER SURVEYThe Anglo-Australian Planet Search began observations in1998January and is currently surveying200stars.Initial results from this work have been published by Tinney et al.(2001).The AAT program stars have been chosen to be among the brightest,chromospherically inactive dwarf and sub-giant stars ranging in spectral type from late F through early M.Most of the stars are south of declination[20¡to prevent overlap with the Keck planet survey(Vogt et al.2000),and most of the stars are brighter than V\7.5,con-sistent with achieving signal-to-noise ratio with(S/N)Z200 exposure times of10minutes or less.This S/N is required to achieve photon-limited precision of3m s~1(Butler et al.1996).High-resolution spectra,R D45,000,are taken with the UCLES echelle spectrometer(Diego et al.1990)on the3.9m AAT.These spectra span the wavelength range from4820 to8550An iodine absorption cell(Marcy&Butler1992) A.provides wavelength calibration from5000to6000TheA.spectrometer point-spread function is derived from the 410TWO NEW PLANETS FROM PLANET SEARCH411detailed shapes of the embedded iodine lines (Valenti,Butler,&Marcy 1995;Butler et al.1996).Similar systems on the Lick 3m and the Keck 10m telescopes currently provide photon-limited precision of 3m s ~1(Butler et al.1996;Butler &Marcy 1997;Vogt et al.2000).No nightly corrections (Walker et al.1995)are applied to the Lick,Keck,or AAT systems.Figure 1shows AAT velocities of four stable dwarf stars with spectral types ranging from late F to early G.The rms of the measured velocities for these stars range from 3.8to 4.9m s ~1,consistent with measurement uncertainties of 3È4m s ~1and intrinsic stellar variability of 2È3m s ~1(Saar,Butler,&Marcy 1998).Of these stars,the F8dwarf HD 196378(HR 7875)was previously reported to be a velocity variable.Kurster et al.(1999)report,““Our best candidate so far for having an orbiting planet is the F8V star /2Pav (\HR 7875).ÏÏThey report a velocity amplitude of 39.5m s ~1and a probable period of 42.5days.Our velocities would have revealed this planet,but we have failed to detect it.Figure 2shows AAT velocities of four stable mid-G dwarfs,while Figure 3shows four stable stars ranging from late G to early K.These stars exhibit a velocity rms ranging from 2.3to 5.0m s ~1,consistent with measurement uncer-tainty of D 3m s ~1.Of these stars,the G8V star q Ceti (HDF IG .1.ÈAAT Doppler velocities of stable late F and early G dwarfs.These observations span the 2.8yr of the AAT Planet Search Project.F IG .2.ÈAAT Doppler velocities of stable G dwarfs10700,HR 509)is frequently used as a velocity standard by precision velocity groups because it is bright,chromo-spherically inactive,and visible from both the northern and southern hemispheres.By the late 1980s the Canada-France-Hawaii Telescope precision velocity survey had shown an rms of 13m s ~1for this star (Campbell,Walker,&Yang 1988;Walker et al.1995).Measurements taken since 1994November from the Lick precision velocity program show an rms of 4.6m s ~1(Butler et al.1996),while the ESO precision velocity program has reported an rms of 14m s ~1for this star (Kurster et al.2000).After 3yr,the AAT velocities for this star have an rms of 3.9m s ~1,as shown in Figure 3.Slowly rotating,chromospherically inactive,main-sequence dwarf stars ranging in spectral type from early G to mid-M have been shown to be intrinsically stable at the 3m s ~1level (Butler &Marcy 1997;Saar et al.1998;Vogt et al.2000;this paper).In addition,Fischer et al.(2001)have shown several class IV subgiants are stable at the 6m s ~1level.In Figure 4we present four stable subgiants from the AAT survey.These stars are stable at the 3È4m s ~1level.With intrinsic stability at this level,it is possible to search for planets around subgiants using the precision Doppler technique.In addition,the stability of such stars makes these stars excellent targets for stellar seismology cam-paigns,especially as they are predicted to have larger ampli-412BUTLER ET AL.Vol.555F IG .3.ÈAAT Doppler velocities of stable late G and K dwarfs tudes than main-sequence dwarfs.Bedding et al.(2001)have recently detected a 17minute oscillation in HD 2151using the AAT Planet Search hardware and software.They took 1200velocity measurements over Ðve nights with an rms of 3.3m s ~1.On a timescale of hours the precision was 2.2m s ~1.3.STELLAR CHARACTERISTICS AND ORBITAL SOLUTIONS3.1.Stellar Characteristics of HD 160691A total of 140observations of HD 160691(HR 6585,HIP 86796,GL 691,k Ara)have been made by Hipparcos (Perryman et al.1997),yielding a distance of 15.3pc and a V magnitude of 5.20.The resulting absolute magnitude is The star is photometrically stable within Hip -M V\4.28.parcos measurement error,with photometric scatter of 0.002mag.The Bright Star Catalog (Hoffleit &Jaschek 1982)assigns a spectral type of G3IV ÈV,in reasonable agreement with the Hipparcos spectral type of G5V.The star is chromospherically inactive,with log R @(HK )\[5.02(Henry et al.1996).Its chromospherically inferred age is D bining Hipparcos astrometry of HD 160691with the SIMBAD radial velocity ([9.0km s ~1)yields an extremely low space velocity with respect to the local standard of rest:U ,V ,W \[4,]3,]3km s ~1.F IG .4.ÈAAT Doppler velocities of stable G subgiantsLike many of the planet-bearing stars,HD 160691is extremely metal-rich.The [Fe/H]derived from high-resolution spectroscopy is 0.28^0.04(Favata,Micela,&Sciortino 1997),in good agreement with our photometric estimate of ]0.29.The lithium line at 6707.8was not A detected in high-resolution (R \100,000)spectra (Favata,Micela,&Sciortino 1996).The mass of HD 160691esti-mated from B [V ,and [Fe/H]is 1.08^0.05M Bol ,M _.3.2.Doppler Velocities and Orbital Fit for HD 160691The 21Doppler velocity measurements of HD 160691obtained between 1998November and 2000November are listed in Table 1and shown graphically in Figure 5.The best-Ðt Keplerian yields an orbital period of 743.5days,a velocity amplitude of 53.6m s ~1,and an eccentricity of 0.62.The minimum (M sin i )mass of the planet is 1.97andM J,the semimajor axis is 1.65AU.The rms to the Keplerian Ðt is 2.98m s ~1,yielding s l2\0.98.3.3.Stellar Characteristics of HD 27442A total of 107observations of HD 27442(HR 1355,HIP 19921,v Ret)have been made by Hipparcos ,yielding a dis-tance of 18.2pc and a V magnitude of 4.55.The resulting absolute magnitude is The star is photo-M V\3.25.metrically stable within Hipparcos measurement error,with photometric scatter of 0.003mag.The Bright Star Catalog assigns this star a spectral type of K2IVa.No.1,2001TWO NEW PLANETS FROM PLANET SEARCH413F IG .5.ÈDoppler velocities for HD 160691.The rms to the best-Ðt Keplerian (solid line )is 3m s ~1.The period is 743.5days,and the semi-amplitude is 53.6m s ~1.Assuming the mass of HD 160691is 1.08theM _,minimum (M sin i )mass of the companion is 1.97and the semimajorM J,axis is 1.65AU.The orbital eccentricity is 0.62,similar to other planets orbiting beyond 1AU.On the basis of measured equivalent widths of Fe lines observed at high resolution (R D 60,000),Randich et al.(1999)determined the metallicity of HD 27442to be [Fe/H]\0.22.This is somewhat more metal-rich than earlier estimates,including Elgaroy,Engvold,&Lund (1999),who report [Fe/H]\0.00based on averaging several previous estimates,and the photometric estimate of Eggen (1993),who found [Fe/H]\0.06.On the basis of evolutionary tracks,Randich et al.(1999)Ðnd the mass of HD 27442to be 1.2^0.1and the age to be 10Gyr,consistent withM _subgiant status.They also report an upper limit for the equivalent width of Li at 3mA .3.4.Doppler Velocities and Orbital Fit for HD 27442Table 2lists the 14Doppler velocity measurements of HD 27442obtained between 1998January and 2001TABLE 1V ELOCITIES FOR HD 160691JDRadial VelocityError ([2,450,000)(m s ~1)(m s ~1)1,118.8874......[4.3 3.31,119.9022......[4.8 2.91,120.8870......[4.7 2.81,121.8928......[4.3 2.91,236.2864......[20.1 4.01,410.8977......[40.8 2.81,412.9773......[41.2 5.51,413.8981......[33.8 2.81,630.3042......46.2 3.31,683.0926......49.0 3.81,684.1320......46.2 4.01,718.1184......33.8 3.61,742.9096......21.1 3.21,743.9240......30.7 3.81,745.0440......19.4 3.21,766.9330......11.3 3.11,767.9689......13.4 3.21,827.8973......0.6 3.01,828.8866...... 6.4 3.81,829.8890......0.0 3.51,855.9058......[1.14.6TABLE 2V ELOCITIES FOR HD 27442JDRadial VelocityError ([2,450,000)(m s ~1)(m s ~1)831.0816........[47.5 2.41,118.1404......[11.52.21,525.9634...... 2.1 2.01,527.0333......[7.5 2.41,630.9035......[44.4 2.21,745.3341......[23.1 2.31,767.3337......[13.5 2.81,768.3132......[17.3 2.51,828.1498......13.2 2.51,830.0084......11.8 3.21,856.1407......19.6 2.61,857.0932......20.1 3.91,919.0796......0.0 2.71,921.1039......3.62.3January.These measurements are graphically shown in Figure 6.The best-Ðt Keplerian yields an orbital period of 415.2days,a velocity amplitude of 32.5m s ~1,and an eccentricity of 0.058.The minimum (M sin i )mass of the planet is 1.35and the semimajor axis is 1.16AU.TheM J,rms to the Keplerian Ðt is 2.96,yielding This iss l2\1.65.F IG .6.ÈDoppler velocities for HD 27442.The rms to the best-Ðt Keplerian (solid line )is 2.9m s ~1.The period is 415.2days,and the semi-amplitude is 32.5m s ~1.Assuming the mass of HD 27442is 1.2theM _,minimum (M sin i )mass of the companion is 1.35The orbit ofthis M J .planet is similar to the Earth in both semimajor axis,a \1.16AU,and eccentricity,e \0.058.This is the only known planet orbiting beyond 0.15AU that is in a circular orbit,similar to solar system planets.TABLE 3O RBITAL P ARAMETERSParameterHD 160691HD 27442Orbital period P (days)............743(10)415.2(5)Velocity amplitude K (m s ~1)......53.6(2)32.5(2)Eccentricity e ........................0.62(0.05)0.058(0.05)u (deg)...............................305(5)347(20)Periastron time (JD)................2,451,626.8(5)2,451,849.3(4)M sin i (M J).........................1.97(0.14) 1.35(0.11)a (AU)............................... 1.65(0.12)1.16(0.11)rms (m s ~1).........................2.982.96414BUTLER ET AL.Vol.555the only planet found to date orbiting beyond0.15AU in an orbit as circular as solar system planets.Orbital parameters for both HD160691and HD27442are listed in Table3.4.ORBITAL SOLUTIONS FOR HD134987,HD13445,HD75289,AND HD17051Keplerian orbital parameters for four previously announced planet candidates have been conÐrmed by our AAT observations.The high precision of these data will be a powerful tool in the search for additional planetary com-panions to these stars.4.1.HD134987The planet orbiting HD134987(HR5657,G5V)was announced from the Keck survey in1999.As outlined in Vogt et al.(2000),this star is similar to51Pegasi in spectral type,enhanced metallicity,and low chromospheric activity.A total of11observations of this star have been made by the AAT between1998April and2000July.These obser-vations are listed in Table4and shown graphically in Figure7.The AAT derived orbital parameters are consis-tent with Vogt et al.(2000).4.2.HD13445A planet orbiting the nearby star HD13445(GL86,HIP 10138,K1V)was announced by the CORALIE team inTABLE4V ELOCITIES FOR HD134987JD Radial Velocity Error([2,450,000)(m s~1)(m s~1)917.2282........0.0 5.61,003.0032......[14.67.21,213.2775......[12.1 4.71,276.0475......[19.2 6.51,382.9573......75.2 5.41,413.8811......30.9 2.51,630.2677......89.3 4.11,683.0609......25.5 5.01,706.0960......[0.6 5.91,717.9564......[4.8 4.31,742.9340......[8.2 3.5F IG.7.ÈDoppler velocities for HD134987(G5V).The solid line is a Keplerian orbitalÐt with a period of264.6days,a semiamplitude of53.7m s~1,and an eccentricity of0.37,yielding a minimum(M sin i)of1.63M J for the companion.The rms of the KeplerianÐt is2.7m s~1.These results are consistent with Vogt et al.(2000).1999(Queloz et al.2000).In addition to the short-period Keplerian orbit,they report a long-term linear trend of [0.36m s~1day~1.The rms to their KeplerianÐt pluslinear trend is7m s~1.This star has been observed23times as part of the Anglo-Australian Survey.These observations are listed in Table5. TheÐrst observation was made in1998January,and the observations span3yr.As shown in Figure8,these obser-vations conÐrm the CORALIE result(Queloz et al.2000). The rms to ourÐt of a Keplerian plus linear trend is3.66m s~1,yielding slightly better than expected based sl2\0.86,on our estimated measurement error.TABLE5V ELOCITIES FOR HD13445JD Radial Velocity Error([2,450,000)(m s~1)(m s~1)831.0350........83.5 4.01,211.9651......338.2 5.71,213.9815......398.5 5.31,214.9298......349.9 4.71,235.9312......[277.2 5.21,236.9078......[333.5 5.51,383.2736......0.0 4.81,387.3139......356.6 4.01,411.2467......[406.7 4.91,413.2313......[255.3 4.01,414.3164......[88.1 4.21,473.0974......[403.8 4.31,525.9320......79.6 4.91,526.9613......207.6 4.81,743.3292......[459.4 6.51,745.2853......[204.5 5.31,828.1337......228.2 5.21,829.0121......213.2 5.41,829.9880......150.5 6.31,856.1052......[160.9 6.21,918.9660......[209.3 4.61,919.9811......[41.7 4.81,921.0019......97.0 5.0F IG.8.ÈPhased Doppler velocities for HD13445(K1V).The solid line is a Keplerian orbitalÐt with a period of15.764days,a semiamplitude of 379m s~1,and an eccentricity of0.046,yielding a minimum(M sin i)of 4.04for the companion.The rms of the KeplerianÐt is3.7m s~1.AM Jlinear trend of[108.1m s~1yr~1has been removed from these velocities. These results are consistent with Queloz et al.(2000),with the possible exception of the linear trend.No.1,2001TWO NEW PLANETS FROM PLANET SEARCH415F IG .9.ÈPhased Doppler velocities for HD 75289(G0V).The solid line is a Keplerian orbital Ðt with a period of 3.508days,a semiamplitude of 56m s ~1,and an eccentricity of 0.01,yielding a minimum (M sin i )of 0.45MJ for the companion.The rms of the Keplerian Ðt is 4.8m s ~1.These resultsare consistent with Udry et al.(2000).Our derived orbital parameters agree with the CORALIE results within measurement error,with the pos-sible exception of the linear trend.The simultaneous best Ðt to the AAT velocities gives a linear trend of [0.296^0.005m s ~1day ~1,about 20%smaller than that,[0.36m s ~1day ~1,found by Queloz et al.(2000)from their CORALIE data.With their lower precision CORAVEL data,they Ðnd a steeper linear trend of [0.5m s ~1day ~1spanning 1980to the present.The trend for HD 13445implies the presence of an additional companion with a period much longer than 10yr and an amplitude greater than 1km s ~1.It could be a low-mass stellar companion (Queloz et al.2000).4.3.HD 75289The CORALIE team (Udry et al.2000)have announced a ““51Peg Èlike ÏÏplanet orbiting the star HD 75289(HR 3497,HIP 43177,G0V).Their observations were carried out between 1998November and 1999October and yield an rms to a Keplerian Ðt of 7.5m s ~1.This star has been observed 13times as part of the Anglo-Australian Planet Search.The Ðrst observation was made in 1998January,and the observations span 3yr.These velocities are listed in Table 6.As shown in Figure 9,these observations conÐrm the CORALIE result.The rms velocity residual to our Keplerian Ðt is 4.82m s ~1,yielding s l2\1.13.TABLE 6V ELOCITIES FOR HD 75289JDRadial VelocityError ([2,450,000)(m s ~1)(m s ~1)830.1656........[0.8 4.6914.9334........[39.8 4.31,212.1495......40.3 6.11,213.1426......[39.9 5.11,214.2518......33.8 6.31,236.9418......15.6 5.81,274.0100......31.78.21,275.9947......[15.2 4.11,631.0085......[25.4 4.91,717.9152......[7.1 5.51,856.2491......27.1 6.31,919.1969......0.0 5.41,920.1472......77.95.2TABLE 7V ELOCITIES FOR HD 17051JDRadial VelocityError ([2,450,000)(m s ~1)(m s ~1)1,118.1146......[55.1 4.41,235.9437......39.5 5.01,383.2779......[71.57.41,413.2245......[72.36.21,473.1000......0.0 4.81,525.9348......47.9 4.61,526.9763......76.1 5.91,743.3364......[32.3 5.91,745.2936......[50.1 5.01,828.1295......66.7 5.61,856.1093......62.5 5.31,856.9355......44.58.61,918.9703......[2.75.44.4.HD 17051In 1998June the ESO Precise Radial Velocity Survey announced a planet orbiting HD 17051(•Hor,HR 810,HIP 12653,G0V)with a 600day orbit (Kurster et al.1999;see also Glanz 1998).On the basis of the same data,they later announced the planet had a period of 320days (Kurster et al.2000).Their data set consists of 95measure-ments taken between late 1992and early 1998.They report a Keplerian semiamplitude of 67m s ~1.The rms velocity residual to their Keplerian Ðt is 27m s ~1,while they esti-mate their measurement error to be 17m s ~1.They attrib-ute the di†erence to stellar activity.A stellar Doppler ““jitter ÏÏof 20m s ~1would account for the di†erence between the internal measurement error and the observed scatter to a Keplerian Ðt.The Anglo-Australian Planet Search began observing HD 17051in 1998November.A total of 13observationsF IG .10.ÈDoppler velocities for HD 17051(G0V).The solid line is a Keplerian orbital Ðt with a period of 312days,a semiamplitude of 63m s ~1,and an eccentricity of 0.15,yielding a minimum (M sin i )mass of 2.13for the companion.The rms of the Keplerian Ðt,10.4m s ~1,is twice the M J internal measurement error,consistent with the observed chromospheric activity and youth of this star.These results are consistent with Kurster et al.(2000).416BUTLER ET AL.Vol.555TABLE 8O RBITAL P ARAMETERSParameterHD 134987HD 13445a HD 75289HD 17051Orbital period P (days).............264.6(5)15.764(0.005)3.508(0.001)312(5)Velocity amplitude K (m s ~1)......53.7(4)379(1)56(1)63(4)Eccentricity e ........................0.37(0.12)0.046(0.002)0.014(0.005)0.15(0.05)u (deg)................................345(10)260(3)309(5)Periastron time (JD)................2,451,628.8(4)2,451,225.1(0.2)2,451,214.5(0.001)2,451,492.8(4)M Star (M _)b .......................... 1.050.8 1.15 1.03M sin i (M J)..........................1.63 4.040.462.13a (AU)................................0.820.1140.0470.91rms (m s ~1)..........................2.733.664.8210.4a Additional slope is [108.1^2m s ~1yr ~1.b Stellar masses from discovery papers.have been made through 2001January,as listed in Table 7and shown in Figure 10.The solid line in Figure 10is the best-Ðt Keplerian to the measured Doppler velocities.Within measurement error,we conÐrm the orbital parame-ters of Kurster et al.(2000).The rms to the Keplerian Ðt to the AAT data is 10.4m s ~1,about twice the estimated measurement error.As Kurster et al.(2000)note,HD 17051is a young,chromospherically active G0V star,consistent with the measured log R @(HK )\[4.65(Henry et al.1996),and a rotation period of 8days (Saar &Osten 1997;Saar et al.1997).Saar et al.(1998)Ðnd the Doppler ““jitter ÏÏcorre-sponding to this level of activity to be 10m s ~1,consistent with the rms to the Keplerian Ðt to the AAT data.Table 8lists the orbital parameters for these four stars based on the AAT measurements.5.DISCUSSIONThe two newly detected planets announced here both orbit beyond 1AU.HD 160691is typical of the examples of such planets discovered to date,moving on a highly ellip-tical orbit.In contrast,HD 27442is in an Earth-like orbit,with a semimajor axis of 1.16AU and an eccentricity of 0.058^0.05(consistent with circular).This is the Ðrst planet to be discovered orbiting beyond 0.15AU in a circu-lar orbit like the planets of our solar system.The AAT data provide the Ðrst conÐrmation of orbital parameters of four planets recently announced from the Keck,CORALIE,and ESO planet searches.In addition,the AAT data appear to rule out the claimed planet around HD 196378.Two broad strategies are being pursued by the various groups carrying out precision velocity surveys.Several groups are carrying out surveys with precision of 10È20m s ~1.There are several advantages to this strategy.Rela-tively low S/N (D 70)spectra,or small wavelength coverage (D 50are required to achieve this level of precision,and A ),data reduction strategies are simpliÐed.A precision of 10m s ~1allows the reliable detection of planets that induce amplitudes of 30m s ~1or larger.Since only these large-amplitude signals are detectable,chromospherically active stars with associated Doppler ““jitter ÏÏof 10È20m s ~1,such as HD 17051,remain viable candidates.The other strategy is to pursue much higher precision,3m s ~1or better.This strategy carries several penalties,including the need for large wavelength coverage (Z 1000high S/N and complex data analysis.The payo†A ),(Z 200),for such a strategy is the ability to detect lower mass planetsin short-period orbits and Jupiter-like planets in distant ([4AU)orbits.To illustrate this,consider the problem of detecting a Jupiter analog.Jupiter induces a Doppler velocity variation in the Sun with an amplitude of 12.5m s ~1.However,the mean expectation value for sin i of n /4reduces this to a typical amplitude of 10m s ~1in a Doppler velocity survey.The top panel of Figure 11shows synthetic observations of a Jupiter analog with a measurement uncertainty of 5m s ~1.The solid line is a best-Ðt Keplerian to this data.The result is an unconvincing 2p detection with no constraint on orbital eccentricity.The lower panel shows the same situation but for 2m s ~1measurement uncertainties.In this case a solid 5p detection is made,and the eccentricity is determined to within ^0.05.The eccentricity of a 3p detec-tion is poorly constrained to within ^0.2.Without know-ledge of the orbital eccentricity,it is not possible to categorize a Jupiter-mass companion at 5AU as a solar system analog.True solar system analogs must reside in circular orbits.The Anglo-Australian Planet Search has been surveying the 200brightest dwarf and subgiant stars ranging in spec-tral type from late F to early M and south of declination [20¡since 1998January.Long-term photon-limited preci-sion of 3m s ~1has been achieved,unique among the southern hemisphere precision velocity surveys.The long-F IG .11.ÈSimulated Jupiter signal observed with a precision of 5and 2m s ~1.Solid lines are best-Ðt Keplerians to the simulated data sets.With measurement precision of 5m s ~1,an unreliable 2p detection is obtained with no information on the orbital eccentricity.With precision of 2m s ~1,a solid 5p detection is made,and the eccentricity is determined to within ^0.05.。