fly out of solar system and the history in 1970s

太空航行历史英语作文The History of Space ExplorationThe exploration of space has been a captivating and awe-inspiring journey for humanity since the dawn of the space age. From the first successful launch of a satellite to the remarkable achievements of modern-day space missions, the history of space exploration is a testament to human ingenuity, determination, and the relentless pursuit of knowledge.The origins of space exploration can be traced back to the early 20th century when visionary scientists and engineers began to seriously consider the possibility of reaching beyond the confines of Earth. In 1903, Russian schoolteacher Konstantin Tsiolkovsky published a groundbreaking paper outlining the theoretical principles of rocket-powered spaceflight. This work laid the foundation for the development of modern rocketry and space technology.The first major milestone in the history of space exploration came in 1957 when the Soviet Union launched Sputnik 1, the world's first artificial satellite. This historic event marked the beginning of the space race, a fierce competition between the United States and theSoviet Union to achieve dominance in space exploration. The launch of Sputnik 1 sparked a flurry of activity as both nations invested heavily in their respective space programs, driven by a desire to demonstrate their technological superiority and geopolitical influence.In the years that followed, a series of remarkable accomplishments occurred in the race to conquer space. The Soviet Union achieved another milestone in 1961 when Yuri Gagarin became the first human to journey into outer space and orbit the Earth. This was followed by the United States' triumph in 1962 when John Glenn became the first American to orbit the planet.The 1960s witnessed a dramatic acceleration in the pace of space exploration as both the United States and the Soviet Union pushed the boundaries of human achievement. The Apollo program, launched by the United States, culminated in the historic Apollo 11 mission in 1969, when Neil Armstrong and Buzz Aldrin became the first humans to set foot on the lunar surface, delivering the iconic words "That's one small step for man, one giant leap for mankind."The exploration of the Moon continued throughout the 1970s and 1980s, with numerous manned and unmanned missions expanding our understanding of the lunar environment. Meanwhile, the development of space-based technologies, such as communicationssatellites and weather monitoring satellites, began to transform our daily lives on Earth.The end of the 20th century ushered in a new era of international cooperation in space exploration. The construction of the International Space Station (ISS) in the 1990s and early 2000s represented a significant milestone, as astronauts and cosmonauts from various nations worked together to establish a permanent human presence in space.In the 21st century, the pace of space exploration has continued to accelerate. Private companies have emerged as key players, complementing the efforts of national space agencies. SpaceX, founded by Elon Musk, has revolutionized the industry with its reusable rocket technology, making space travel more affordable and accessible.Robotic missions have also played a crucial role in expanding our understanding of the solar system and beyond. Probes like Voyager, Cassini, and New Horizons have sent back breathtaking images and invaluable data from distant planets and celestial bodies, furthering our scientific understanding of the universe.The future of space exploration holds even more exciting possibilities. Plans are underway for ambitious missions to Mars, with the ultimategoal of establishing a human presence on the red planet. The development of advanced technologies, such as nuclear-powered spacecraft and advanced propulsion systems, promises to unlock new frontiers of exploration.As we look to the future, the history of space exploration serves as a testament to the human spirit of adventure, curiosity, and the relentless pursuit of knowledge. The journey to the stars has been filled with triumphs and setbacks, but through it all, humanity has demonstrated its unwavering determination to explore the unknown and push the boundaries of what is possible. The story of space exploration is one of hope, inspiration, and the boundless potential of the human mind.。

myday作文英语初一关于上学全文共6篇示例，供读者参考篇1My Day at SchoolI wake up at 6:30 every morning because I have to get ready for school. First, I brush my teeth and wash my face. Then I get dressed in my school uniform - a white shirt, navy blue pants, and black shoes.My mom makes me breakfast - usually an egg sandwich or oatmeal with fruit. I eat quickly because I don't want to be late for school. At 7:15, I put on my backpack and my mom walks me to the corner to wait for the school bus.The big yellow bus arrives at 7:30 and I get on and find a seat near the back with my friends Michael and Samantha. We talk and laugh together on the ride to school. Sometimes I look out the window at all the buildings and traffic we pass.We arrive at Parker Elementary School at 8:00. I get off the bus and line up with my class in the courtyard. At 8:15, the bellrings and we follow our teacher, Mrs. Roberts, inside to our classroom.The first class of the day is English. We practice reading out loud from our books and learn new vocabulary words. Mrs. Roberts puts sentences on the board and we have to identify the nouns, verbs, adjectives, and other parts of speech.After English, we have math class at 9:30. We learn how to add and subtract bigger numbers. Sometimes we use blocks or drawings to help us understand. We also practice telling time on analog clocks. Math is not my favorite subject because I find it a bit confusing sometimes.At 10:30, we get a 15 minute snack break. I usually have an apple or some crackers that my mom packs for me. We can play outside for a few minutes too before lining up again to go back inside.The next class is science at 10:45. We just started a unit about the human body. We learned about the skeletal system and all the bones we have. We even got to look at a plastic model skeleton up close! Science is really interesting.After science, we have social studies at 11:45. We are studying map skills and the countries of North America right now.I like coloring in the maps and trying to memorize all the state capitals.At 12:30, we get ready to go to the cafeteria for lunch. My favorite lunch is pizza day! I also like the chicken nuggets but I don't really like the meatloaf. We have 30 minutes to eat and then we can go out to the playground for 25 minutes of recess. Recess is probably my favorite part of the school day because I can run around and play games like tag and kickball with all my friends.After recess, we go back inside for music class at 1:30. We sing fun songs and learn about notes and rhythms. Sometimes we even get to play simple instruments like triangles, tambourines, or egg shakers.Art class is next at 2:15. We do all kinds of art projects like painting, drawing, making sculptures out of clay or recycled items. We get very creative and messy sometimes! I love art because I'm a good artist and it lets me express myself.After art, we have PE or gym class at 3:00. We run laps, play games, and exercise to stay healthy. PE can be kind of tiring but it's fun. I'm pretty good at sports like basketball and soccer.Finally, the last class of the day is at 3:45. It's either writing, spelling, or reading skills. We practice our handwriting, spelling words, and working on our reading comprehension. These are important skills to keep practicing.At 4:30, the bell rings and it's time to get ready to go home! I pack up my backpack and line up with my class. We go out to the courtyard to wait for our bus numbers to be called. I have to wait about 15 minutes for my bus (#24) to arrive.Once I'm on the bus, I feel tired from my busy day at school. The bus drops me off at my corner at 5:00 and I walk the short distance home with my mom waiting for me. I'm starving so I have a snack like apple slices and peanut butter when I get home.Some days I have activities after school like soccer practice or art class. But on days with no activities, I get to rest and play at home. I love school but I'm always glad when the weekend finally arrives!That sums up a typical day for me in 5th grade at Parker Elementary. Going to school is hard work but I'm learning so much. I get to see my friends, study interesting subjects, and have fun too. I just have to make sure I get a good night's sleep so I'm ready to do it all over again tomorrow!篇2My Day at SchoolAh, the familiar sound of my alarm clock blaring at 6:30 am! It's time to start another day at school. I groan and try to hit the snooze button, but my mom's voice rings out from the kitchen, "Time to get up, sleepyhead!"Reluctantly, I drag myself out of bed and shuffle towards the bathroom. After a quick shower and brushing my teeth, I feel a little more awake. I put on my school uniform – a crisp white shirt, navy blue shorts, and my favorite pair of sneakers.Downstairs, the aroma of freshly brewed coffee and sizzling bacon fills the air. My mom has prepared a hearty breakfast, as always. I gobble down my scrambled eggs and toast, washing it down with a glass of orange juice."Don't forget your lunchbox," mom reminds me as I stuff my books and notebooks into my backpack. I quickly grab the colorful lunchbox from the counter and give her a peck on the cheek."Thanks, mom! See you later!" I call out as I rush out the door.The walk to school is always an adventure. I meet up with my best friend, Jake, at the corner, and we chat excitedly about the upcoming science fair. Jake has this crazy idea of building a volcano that actually erupts, and I can't wait to see if it works.As we approach the school gates, the familiar sight of kids running around, teachers ushering them inside, and the sound of the morning bell greets us. We hurry to our classroom and take our seats just as our teacher, Mrs. Robinson, walks in."Good morning, class!" she says with a warm smile. "I hope you're all ready for an exciting day of learning."The first few periods fly by in a blur of lessons on grammar, mathematics, and history. My favorite part of the day is always the recess break. Jake and I race to the playground, where we join our friends for a game of tag or kickball.After recess, we have science class, which is undoubtedly the highlight of my day. Today, we're learning about the solar system, and Mrs. Robinson has brought in a big model to demonstrate the planets' orbits around the sun. I'm fascinated by the vastness of space and can't wait to become an astronaut someday.Lunchtime rolls around, and we all gather in the cafeteria. I trade my peanut butter and jelly sandwich for Jake's bag of chips,and we devour our lunches while chatting about the latest episode of our favorite cartoon show.The afternoon passes quickly with lessons on art, music, and physical education. In art class, we're working on a project where we have to create a self-portrait using different materials. I decide to use colorful yarn and buttons to make my portrait extra special.Finally, the last bell rings, signaling the end of the school day. Jake and I say goodbye to our classmates and start the walk home, discussing our plans for the weekend.As I approach my house, I can already smell the delicious aroma of mom's famous spaghetti and meatballs wafting through the air. I can't wait to tell her all about my day and the exciting things I learned.School days can be tiring, but they're also filled with so much fun, laughter, and learning. I wouldn't trade them for anything in the world!篇3My Day at SchoolHello! My name is Emma and I'm 11 years old. I'm in my last year of primary school and I want to tell you all about a typical day for me. Get ready, because my days are pretty jam-packed!The Morning RushMy day starts at 6:30am when my mom comes into my room and says "Time to get up, sleepyhead!" I groan and pull the covers over my head, never wanting to leave my cozy bed. But mom is persistent, so I eventually drag myself up and get ready for the day ahead.After brushing my teeth and combing my crazy bedhead hair, I head to the kitchen for breakfast. My favorite is waffles with syrup and berries! I'll take anything sugary to help wake me up in the morning. While I'm stuffing my face, mom packs my lunch and reminds me to grab my homework and anything else I need for school.By 7:45am, I'm dressed and ready to go. I put on my backpack, give my baby brother Daniel a kiss goodbye, and wait impatiently by the door for dad to pull the car around. The drive to school takes about 15 minutes, which I spend listening to music or reading to get my brain working.The Rolling Academic MarathonI arrive at school by 8:15am, just in time for the first bell. I meet up with my best friends Sophia and Jake and we head to our first class together - math. Now don't get me wrong, I actually really like math and numbers. But Miss Johnson has a way of making even the simplest equations seem confusing!By 9:45am, math class is finally over and I hardly have time to catch my breath before English literature at 10am. Mrs. Phillips is my favorite teacher and she always gets us really into analyzing the books we read. Today we're discussing Charlotte's Web which is one of my all-time favorite stories. I can't wait to debate whether Wilbur the pig should have really been saved!After literature, it's time for science at 11:30am. Mr. Davies is the science teacher and he's...let's just say he's a little weird. But his experiments are always super cool and hands-on, so I can't complain too much. Today we're dissecting owl pellets which is both totally gross but fascinating at the same time.By noon, I'm starving so I scarf down the lunch mom packed - a sandwich, fruits, veggie sticks, and a cookie for dessert. I spend lunchtime hanging out with Sophia and Jake, chatting about our favorite TV shows and making plans for that weekend. Sometimes we play basketball in the gym if it's raining outside.The afternoon classes consist of history at 12:45pm where we're learning about ancient Rome. It's not my favorite subject since I find it a bit boring, but I still pay attention.Then at 2pm it's art class which is a nice way to relax the mind. I love getting creative with paints, clay, and any other materials Mrs. Thomas provides. We're working on self-portraits using oil pastels this week.Finally, the last class of the day rolls around at 3:15pm - music. This is definitely one of my favorites because I just love singing and playing instruments like the recorder and hand drums. Plus, Miss Kate makes it really fun with all the warm-up games and activities she plans.By 4:30pm, the final bell rings and I could not be more relieved! After putting away my books, I meet my parents out front and we head home, chatting about the highlights of my day over snacks in the car.The Evening Wind-DownOnce home around 5pm, I take an hour or so to just veg out and have some free time. I'll watch a show, play outside, or read comics - whatever I feel like that allows my brain to rest after being "on" all day.Then it's time for dinner around 6:30pm. We'll all sit together as a family, discussing our days and telling funny stories. Mom and dad like to quiz Daniel and me on what we learned in school that day too.After dinner, I take a bath and get into my coziest pajamas. I spend some time on any homework I have, calling friends to get assistance if I need it. Depending on my workload, I may get a bedtime snack like ice cream if I'm being good!Finally, I'm tucked into bed by 9pm, exhausted but satisfied after a productive day. I read for a little bit to wind down before drifting off to sleep, knowing I'll wake up and do it all again tomorrow. Phew, being a kid sure does take a lot of effort! But I won't have it any other way.篇4My Day at SchoolI wake up to the sound of my alarm clock blaring at 6:30 AM.I groan and hit the snooze button, wishing I could sleep in for just a little while longer. But I know that if I don't get up now, I'll be late for school. So, with great reluctance, I drag myself out of bed and stumble into the bathroom to brush my teeth and splash some water on my face.After getting dressed in my school uniform – a white shirt, navy blue pants, and a tie that I never seem to get quite right – I head downstairs for breakfast. Mom has made my favorite, pancakes with maple syrup and a glass of orange juice. I wolf it down quickly, knowing that if I don't hurry, I'll miss the school bus.I grab my backpack, which feels like it weighs a ton with all the books and notebooks crammed inside, and rush out the door. Just篇5My Day at SchoolBrrrrrring! The shrill sound of my alarm clock jolts me awake at 6:30am. I groan and pull the covers over my head, trying to cling to the last few moments of sleep. But then I remember - it's a school day! I hop out of bed, full of energy and excited for the day ahead.I race to the bathroom to brush my teeth and splash some water on my face to fully wake up. My hair is a total mess, so I spend a few minutes brushing and styling it before heading downstairs for breakfast. The smell of pancakes and syrup wafts through the air - yum!"Good morning, sweetheart!" my mom says in a singsong voice as I enter the kitchen. "Did you sleep well?" I nod vigorously as I plop down at the table and dig into the fluffy pancakes. My little sister is already there, syrup smeared across her cheeks as she gobbles down her food.All too soon, it's time to go. I grab my backpack and lunchbox and head out the door with Mom. The morning air is crisp and cool. I take a deep breath, feeling the freshness fill my lungs. School is only a few blocks away, so we walk briskly down the sidewalk.When we arrive, the schoolyard is already a chaotic blur of running, screaming kids. I spot my best friend Timmy and his brother Tommy and rush over to say hi. We chat and joke around until the warning bell rings. "Better get to class!" Timmy shouts over the noise. We wave goodbye to our parents and hurry inside.My first class is math. I actually really enjoy math - it's like a giant puzzle that needs solving. Today we're learning about fractions. I sit up straight, determined to understand every concept. Mrs. Ellis writes out some examples on the board, and I copy them down diligently in my notebook. When she calls onme, I'm able to recite the right answer. Yes! I love that feeling of getting it right.After an hour, it's time for reading class with Mr. Parker. We're in the middle of a really cool book about adventurers exploring a dense jungle. Mr. Parker has such an animated way of reading - he does all the voices and everything! As he reads aloud, I'm utterly transported to that steamy jungle world. I can vividly picture the massive trees, strangling vines, and glimpses of exotic animals.The morning flies by with science, where we learn about the life cycle of butterflies, and art, where we sculpt clay figures. Before I know it, it's lunchtime! I grab my lunchbox from my cubby and race outside to the playground. Timmy and Tommy are already there, and we claim our usual spot under the big oak tree.I'm starving, so I waste no time devouring my peanut butter and jelly sandwich, baby carrots, and an apple. We spend the rest of the break playing a rousing game of kickball with some of the other kids. I manage to kick the ball amazingly far - definitely one of my proudest moments!The bell rings, signaling the end of lunch. I groan inwardly, wishing I had more time. But I perk up when I remember we havegym class next with Coach Richards. That's probably my favorite class ever!Today, we're playing dodgeball. The two team captains get picked, and then we're chosen one by one. "Dylan!" shouts Bobby, one of the captains. Yes! I was picked early this time. I grin and join my teammates on the side.The game is pure madness - balls whizzing everywhere, kids scattering and diving for cover. I manage to nail a few opponents, but eventually get pegged right in the stomach. I'm out, but it was totally worth it! What a blast.After gym, it's time for the last class of the day: history with Mr. Nguyen. We're learning about ancient Egypt and the pharaohs who ruled over the empire. I try my best to follow along, but to be honest, it's hard to focus after such an energetic gym period. My mind keeps wandering, thinking about playing outside after school.At long last, the final bell rings at 3:00pm. I practically fly out of my seat and out the door, relishing my newfound freedom. The bright sunshine greets me as I burst outside, instantly feeling rejuvenated.Mom is there to pick me up. "How was your day, kiddo?" she asks as we start walking home. I launch into an enthusiastic recap, telling her every single detail from start to finish. She listens patiently, smiling and nodding along.Once we're home, I toss my backpack aside and immediately head out to the backyard. Time to play basketball, my current obsession! I practice dribbling skills and shooting hoops until I've worked up a serious sweat.Sometime later, Mom pokes her head out to call me in for dinner. Finally, I'm able to rest! We enjoy a yummy meal of Mom's famous spaghetti and meatballs, chatting about our days.After dinner, I finish up any homework I have, then get ready for bed. I snuggle under the covers, my body deliciously tired. I reflect on what an awesome day it was - the learning, the playing, the time with friends. I can't wait for another fun-filled day at school tomorrow!篇6My Day at SchoolWaking up in the morning is always hard for me. My mom has to come into my room and shake me awake. "Time to get upfor school, sleepyhead!" she says in a cheerful voice. I just groan and pull the covers over my head. School sounds like the worst thing in the world when I'm still half-asleep.But mom is pretty persistent. She peels back my cozy covers and tickles my side until I can't stop giggling. "Okay, okay, I'm up!" I finally cry out between laughs. Slowly, I drag myself out of bed and into the bathroom to get ready.After I'm dressed in my school uniform, I head to the kitchen for breakfast. The smell of mom's pancakes instantly makes my mouth water. She makes the fluffiest, most delicious pancakes with gooey chocolate chips in them. My favorite! I quickly scarf them down, get my backpack, and give mom a sticky kiss on the cheek before rushing out the door.The school bus is already waiting for me outside. I wave goodbye to mom and hurry to take my usual seat near the back. Simon and Emma are there saving me a spot between them, like always. Simon farts loudly as I sit down and we all crack up laughing. Gross, but hilarious!"Did you finish the math homework?" Emma asks me as the bus rumbles down the road. I nod and pull the crumpled assignment out of my backpack to show her. Emma is thesmartest kid in our class and always gets perfect scores. Simon and I just copy her work most of the time. Shhh, don't tell!When we finally get to school, the three of us race each other to our classroom door. I'm always the slowest runner and come in last. Mrs. Taylor is waiting for us with a warm smile on her face. "Good morning, scholars! I hope you're ready for an exciting day of learning," she says in a sing-song voice. Mrs. Taylor is my favorite teacher ever. She makes every subject seem fun, even the boring stuff like grammar and fractions.Our first lesson is reading. We're working our way through the Harry Potter books, which I just can't get enough of. Mrs. Taylor has a really animated way of reading out loud and doing all the character voices. It's like the story just comes alive! After she reads a chapter, we break into groups to discuss what we think will happen next. I love hearing all the crazy theories people come up with.Math is up next, which is definitely not my strongest subject. There's just something about all those numbers and symbols that makes my brain hurt. But Mrs. Taylor has lots of little tricks to make it easier, like using food examples or turning it into a game. Today we're learning about fractions by sharing granolabars and taking turns. I end up with a bunch of crumbs all over my desk, but it actually helps me understand!My favorite part of every day is outdoor recess time after lunch. I bolt out to the playground equipment as soon as the bell rings, racing Simon and Emma to claim the best swings or dibs on the tetherball. We run around wildly, working up huge appetites. I'm always drenched in sweat and my cheeks get all red, but I just feel so free and happy. Before we know it, the dreaded bell is ringing again to call us back inside. We groan and drag our tired bodies back to class, already counting down to when we can play again tomorrow.The afternoon is a blur of social studies, science experiments, and English lessons on things like adjectives and compound words. Sometimes my mind wanders no matter how fun the teachers try to make it. I start daydreaming about what games I'll play on the playground tomorrow or whether my mom is baking fresh cookies for an after-school snack. A light tap on my arm brings me back to reality as Mrs. Taylor calls on me to answer a question. Oops, I have no clue what she just asked!Finally, the clock strikes 3pm and it's time for the best part of the day...the final bell! All the kids cheer as we're officially freed from our lessons. I grab my backpack and make a mad dash forthe bus waiting outside with Emma and Simon on my heels. We scramble aboard and get to re-live some of the highlights of our day, gossiping about other kids and rehashing the funniest jokes. The bus ride just flies by in what feels like two minutes.When I get dropped off at my driveway, I see my mom's face already pressed against the window waiting for me. She rushes out for a big hug as soon as my feet hit the pavement. "How was your day, sweetie?" she asks, ruffling my sweaty hair. I give her one of those looks that says everything...exhausting and exhilarating all at once.I can't wait to just veg out on the couch watching cartoons for a while. Maybe after a snack and a shower, I'll start any homework I have. Or maybe I'll just take a nap. After。

Mercury 水星(英)Mercury is the closest planet to the Sun and the eighth largest. Mercury is slightly smaller in diameter than the moons Ganymede and Titan but more than twice as massive.orbit: 57,910,000 km (0.38 AU) from Sundiameter: 4,880 kmmass: 3.30e23 kgIn Roman mythology Mercury is the god of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes, the messenger of the Gods. The planet probably received this name because it moves so quickly across the sky.Mercury has been known since at least the time of the Sumerians (3rd millennium BC). It was given two names by the Greeks: Apollo for its apparition as a morning star and Hermes as an evening star. Greek astronomers knew, however, that the two names referred to the same body. Heraclitus even believed that Mercury and Venus orbit the Sun, not the Earth.Since it is closer to the Sun than the Earth, the illumination of Mercury's disk varies when viewed with a telescope from our perspective. Galileo's telescope was too small to see Mercury's phases but he did see the phases of Venus.Mercury has been visited by only one spacecraft, Mariner 10. It flew by three times in 1974 and 1975. Only 45% of the surface was mapped (and, unfortunately, it is too close to the Sun to be safely imaged by HST). A new discovery-class mission to Mercury, MESSENGER was launched by NASA in 2004 and will orbit Mercury starting in 2011 after several flybys.Mercury's orbit is highly eccentric; at perihelion it is only 46 million km from the Sun but at aphelion it is 70 million. The position of the perihelion precesses around the Sun at a very slow rate. 19th century astronomers made very careful observations of Mercury's orbital parameters but could not adequately explain themusing Newtonian mechanics. The tiny differences between the observed and predicted values were a minor but nagging problem for many decades. It was thought that another planet (sometimes called Vulcan) slightly closer to the Sun than Mercury might account for the discrepancy. But despite much effort, no such planet was found. The real answer turned out to be much more dramatic: Einstein's General Theory of Relativity! Its correct prediction of the motions of Mercury was an important factor in the early acceptance of the theory.Until 1962 it was thought that Mercury's "day" was the same length as its "year" so as to keep that same face to the Sun much as the Moon does to the Earth. But this was shown to be false in 1965 by doppler radar observations. It is now known that Mercury rotates three times in two of its years. Mercury is the only body in the solar system known to have an orbital/rotational resonance with a ratio other than 1:1 (though many have no resonances at all).This fact and the high eccentricity of Mercury's orbit would produce very strange effects for an observer on Mercury's surface. At some longitudes the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while the stars would be moving three times faster across the sky. Observers at other points on Mercury's surface would see different but equally bizarre motions.Temperature variations on Mercury are the most extreme in the solar system ranging from 90 K to 700 K. The temperature on Venus is slightly hotter but very stable.Mercury is in many ways similar to the Moon: its surface is heavily cratered and very old; it has no plate tectonics. On the other hand, Mercury is much denser than the Moon (5.43 gm/cm3 vs 3.34). Mercury is the second densest major body in the solar system, after Earth. Actually Earth's density is due in part to gravitational compression; if not for this, Mercury would be denser than Earth. This indicates that Mercury's dense iron core is relatively larger than Earth's, probably comprising the majority of the planet. Mercury therefore has only a relatively thin silicate mantle and crust.Mercury's interior is dominated by a large iron core whose radius is 1800 to 1900 km. The silicate outer shell (analogous to Earth's mantle and crust) is only 500 to 600 km thick. At least some of the core is probably molten.Mercury actually has a very thin atmosphere consisting of atoms blasted off its surface by the solar wind. Because Mercury is so hot, these atoms quickly escape into space. Thus in contrast to the Earth and Venus whose atmospheres are stable, Mercury's atmosphere is constantly being replenished.The surface of Mercury exhibits enormous escarpments, some up to hundreds of kilometers in length and as much as three kilometers high. Some cut thru the rings of craters and other features in such a way as to indicate that they were formed by compression. It is estimated that the surface area of Mercury shrank by about 0.1% (or a decrease of about 1 km in the planet's radius).One of the largest features on Mercury's surface is the Caloris Basin (right); it is about 1300 km in diameter. It is thought to be similar to the large basins (maria) on the Moon. Like the lunar basins, it was probably caused by a very large impact early in the history of the solar system. Weird terrain opposite Caloris Basin That impact was probably also responsible for the odd terrain on the exact opposite side of the planet (left).In addition to the heavily cratered terrain, Mercury also has regions of relatively smooth plains. Some may be the result of ancient volcanic activity but some may be the result of the deposition of ejecta from cratering impacts.A reanalysis of the Mariner data provides some preliminary evidence of recent volcanism on Mercury. But more data will be needed for confirmation.Amazingly, radar observations of Mercury's north pole (a region not mapped by Mariner 10) show evidence of water ice in the protected shadows of some craters.Mercury has a small magnetic field whose strength is about 1% of Earth's.Mercury has no known satellites.Mercury is often visible with binoculars or even the unaided eye, but it is always very near the Sun and difficult to see in the twilight sky. There are several Web sites that show the current position of Mercury (and the other planets) in the sky.More detailed and customized charts can be created with a planetarium program.。

我想成为一名宇航员八上英语作文全文共5篇示例，供读者参考篇1My Dream of Becoming an AstronautEver since I was a tiny kid, I've always looked up at the night sky and wondered what it would be like to fly up there among the stars. The thought of soaring through space in a rocket ship and getting to see the whole Earth down below just seems so amazing to me. That's why my biggest dream is to become an astronaut when I grow up!I've loved learning about space and planets and rocket ships for as long as I can remember. When I was really little, my parents would read me books about the solar system before bedtime. I could spend hours just staring at the colorful pictures of Saturn's rings or the craters on the moon. In kindergarten, I remember doing an art project where we made paper mache models of the planets. I worked super hard on making my model of Jupiter with its big red spot. The teacher said she was really impressed!In first grade, we went on a field trip to the science museum and I got to see a real spacecraft up close. It was so huge! The guide told us all about how the rocket engines work by burning fuel to provide thrust. He let us try on space helmets and bunny suits too. I didn't want to take mine off! From then on, I was completely hooked on anything related to space travel and exploration.My favorite TV show is the animated one about those two kids who go on crazy adventures throughout the galaxy with their alien friend. I have all the action figures from that show. I also really like watching videos of real rocket launches. It's just so cool seeing those giant machines blast off into the sky with an awesome roar while big clouds of smoke trail behind. I could watch launch videos over and over and never get bored.In second grade, we had to write about what we wanted to be when we grew up. Of course, I wrote that I want to be an astronaut! I drew a picture too of me floating around inside a space shuttle. Mrs. Thompson really liked my essay and drawing. She told my parents I did a great job explaining why I have that dream.Last summer, my family took a trip down to Florida and we got to go on a tour at the Kennedy Space Center. That place islike heaven for anyone who's obsessed with space like me! We saw real rocket boosters and got to experience a simulation of an actual launch. We also walked through a full-size model of a space station. I sat in the commander's seat and pretended I was piloting the mission. The guide said I could make a great astronaut someday with how much I already know.This year in science class, we've been learning all about gravity and thrust and aerodynamics and stuff. I find it all super fascinating, especially the experiments we get to do. A few weeks ago, we made stomp rockets out of soda bottles. When you stomp on the bottle, it causes a buildup of air pressure that propels the rocket up into the air. I had the fourth highest flying rocket in the class! The great thing about science is how it explains why and how things work through observable facts and testing hypotheses. That's going to be really important knowledge for me as an astronaut.Speaking of important knowledge and skills, I've also been working really hard on studying and getting excellent grades. Astronauts have to be really smart in basically every subject, but especially science, technology, engineering, and math. I get good marks in all those areas. My absolute favorite is physics though. Learning about forces, motion, energy, and theproperties of planets and stars will definitely come in handy. I'm even taking extra coding lessons to learn programming languages that I can use to command computer systems.Being an astronaut isn't just about brains though. You also have to be in peak physical condition. Since I'm really active and play lots of sports, I've got that part covered. Every day after school, I go running for miles to build up my cardiovascular endurance. I'm also on the school's swim team, which is great for muscle strength and staying in shape. On the weekends, my dad takes me hiking and rock climbing to work on agility, balance, and coordination. Astronauts need to be able to move skillfully in low-gravity environments.There are so many exciting reasons why I want this career so badly. Can you imagine how thrilling it would be to actually leave planet Earth and soar through the cosmos? Or walk in space outside your spacecraft looking down at our home planet from above? What about getting to pilot futuristic vehicles and conduct experiments in a whole new frontier? Maybe I'd even get to take the first steps on Mars or an asteroid someday! That would be one giant leap for kid-kind, that's for sure.I also think being an astronaut sounds like one of the most meaningful jobs out there. Space explorers help expandhumanity's knowledge and understanding of the universe. Their bravery allows the rest of us to learn more about our solar system and beyond from the safety of Earth. Astronauts are at the forefront of scientific discovery and space-based research that could lead to amazing new technologies to help make life better. How cool would it be to be part of something that important?Now, I know becoming an astronaut won't be easy at all. The training process is incredibly difficult and competitive. You have to be absolutely brilliant and in perfect health, both physically and mentally. There's also a lot of rigorous studying and skills tests to pass first. I'm sure it will require many long years of hard work and total dedication to achieve this ambitious goal.But I'm more than ready to give it my all and overcome any obstacles or challenges in my way. My dream of journeying into space as an astronaut means that much to me. I've had this driving passion for as long as I can recall. It's what motivates me to study hard, stay active, and learn everything I can about STEM subjects. I'm determined to make the cut someday and have my own spacesuit with my name stitched onto it. Nothing is going to stop me from reaching for the stars!篇2My Dream of Becoming an AstronautHi there! My name is Emily and I'm 10 years old. I go to Oakwood Elementary School and I'm in 5th grade. Today I want to tell you all about my biggest dream - to become an astronaut when I grow up!Ever since I was a tiny kid, I've been obsessed with space. I remember lying outside on warm summer nights with my dad, staring up at the twinkling stars in the dark sky. He would point out the constellations to me - Orion, the Big Dipper, Cassiopeia. I was always amazed that those stars were actually huge suns super far away. Some were already dead by the time their light reached us! The universe is just so mind-blowingly big and mysterious.In second grade, we went on a field trip to the science museum. That's when I first saw real spacesuits and rocket models up close. The guide told us how astronauts have to be super smart and brave to travel to space. From that moment on, I knew - that's what I wanted to do with my life! Nothing could be more exciting than blasting off in a rocket and floating around outside our planet.After that field trip, I started reading everything I could about space travel. I checked out a huge stack of books from thelibrary all about the moon landings, the space shuttles, the International Space Station, and future plans for Mars missions. My favorite was a big picture book filled with gorgeous photos of faraway galaxies and nebulae captured by the Hubble Space Telescope. Looking at those images of swirling colors and strange shapes in the deep unknown made me feel so small - and yet so curious to explore it all!I also started paying extra attention in my science and math classes at school. You have to be really good at those subjects to have a chance at becoming an astronaut. Luckily, I find them super interesting, especially our units on physics, astronomy, and engineering. It's amazing to learn about things like Newton's laws of motion, how rocket engines work by blasting hot gases, and what it takes to leave Earth's gravitational pull. I always ask my teachers a ton of questions because I want to understand every little detail. Knowledge is power when you're shooting for the stars!Outside of school, I joined our city's rocket club for kids. We get to build and launch small model rockets every week. It's awesome seeing the different designs and figuring out through trial-and-error how to make them go higher and faster. I've already won a few contests! Next summer, I'm going to rocketcamp where I'll learn more advanced skills like making payloads and parachute recoveries. Becoming an astronaut is my one true goal and I'm going to work as hard as I can to make it happen.I know there are a lot of challenging steps along the way. First, I'll have to get excellent grades all through middle school, high school, and college. Astronauts need to earn degrees like a Bachelor's in a field like Aerospace Engineering and then even a Master's or Doctorate. I'm prepared to stay focused and be a super dedicated student for many years to come.After graduating from multiple universities, the really hard part is getting selected by NASA or another space agency to join their astronaut corps. That's because there are way more applicants than open slots, and they only choose the most qualified and mentally tough people. I'll have to become an expert in super difficult subjects like orbital mechanics, aircraft operations, survival skills, and speaking Russian! Not to mention passing intense physicals and mental tests. I'm ready to put in the blood, sweat and tears it will take to rise above the rest.If I do make it through that extremely competitive process, then I'd finally achieve my lifelong dream - getting assigned to a space mission! Can you imagine? Despite months of hardcore training and preparation, nothing could prepare you for thatmoment when the countdown ends, the engines ignite, and you get blasted away from Earth. Up, up through the clouds, the sky turning darker until there's nothing but silent blackness and stars all around you. That first glimpse of our planet, a bright blue marble hanging in the void, would be the most beautiful sight in the universe.Once in space, every day would be filled with new challenges and wonders. Maybe one mission would be doing important scientific experiments aboard the International Space Station. Studying things like human health, new medicines, or materials in microgravity could lead to discoveries that help make life better for everyone on Earth. Or maybe I'd get to be one of the first explorers on Mars or another planet! Just think of being the first person to set foot somewhere no human has gone before. Collecting and analyzing alien soil and rock samples, setting up habitats for people to eventually live on another world. It would be like science fiction coming true!Even if it's "just" repairing and upgrading satellites or something, it would still be an incredible honor to journey to space and use cutting-edge technology. Every kid who has ever looked up at the night sky dreaming of exploring strange newworlds would be jealous! I would feel like one of the luckiest people ever.Of course, being an astronaut is also extremely dangerous. There are terrifying risks like engine failures, space debris hitting you, solar radiation exposure, and cabin leaks causing loss of oxygen. If a mission goes wrong, you could end up stranded and alone billions of miles from home. But I'm not going to let the possibility of peril scare me off of my greatest ambition. The chance to make history and push the boundaries of human potential is worth the risk in my mind. Plus, wouldn't it be amazing to go out exploring and advancing humanity's journey among the stars?So that's my vision for my future career and why I dream of being an astronaut more than anything! It combines my endless curiosity about the cosmos, my talents in math and science, and my spirit for adventure and discovery. I'm going to spend the next decade nose-to-the-grindstone learning as much as I possibly can in school. Then I'll use that knowledge and apply it with every ounce of determination I've got to make the cut and join a space program. Even if it ends up taking several tries, I'll never, ever give up until I've earned my place among the elite few who have looked down upon our Earth from the heavens. Toboldly go where very few people have gone before - that's my ultimate calling and I can't wait to reach for the stars!篇3My Dream to Become an AstronautHave you ever looked up at the night sky and wondered what it would be like to travel to space? I sure have! Ever since I was a little kid, I've dreamed of becoming an astronaut. Floating around in zero gravity, looking down at our beautiful planet Earth from the windows of a spaceship or space station – how amazing would that be?I've always been fascinated by space and everything to do with it – planets, stars, galaxies, black holes, you name it. I love learning about all the cool discoveries scientists have made by sending robotic rovers to explore Mars or by using powerful telescopes to peer into the farthest reaches of the universe. But as exciting as those robotic space missions are, I don't want to just read about space exploration – I want to experience it for myself!I can't really put my finger on what sparked my interest in space and astronauts in the first place. Some of my earliest memories are of watching rocket launches on TV with myparents and being in total awe. The incredible power and energy required to escape Earth's gravity and soar into the inky blackness of space. The bravery of those astronauts strapped to those controlled explosions, risking everything to push the boundaries of exploration. It all seemed so heroic and adventurous.That's when I decided that someday, I too wanted to be one of those adventurers among the stars. I started devouring books about space from the local library. I would spend hours building model rockets and pretending to be an astronaut duringmake-believe playtime. On career day at school, while the other kids dressed up as firefighters or veterinarians, I went decked out in a makeshift spacesuit constructed from recycled materials. Let's just say it didn't win any fashion awards, but it sure did turn some heads!As I've gotten a little older, my enthusiasm for space and my dream of becoming an astronaut has only continued to grow stronger. I'm at the top of my class in math and science, especially physics. Launching rockets and studying the principles of thrust, trajectories, orbital mechanics – that's my idea of a good time! I've joined the astronomy club and saved up money from my allowance and doing chores to buy a small backyardtelescope, which I use to gaze at planets, stars, nebulae, and more every clear night.But it's not just the adventure and excitement of space travel that draws me in. I also believe that space exploration is crucial for the future of humanity. We can't stay confined to this one planet forever – our curiosity and drive to discover has always pushed us to explore new frontiers. Plus, we're going to need new resources and room to grow as our population and consumption levels keep increasing here on Earth. By learning about and eventually visiting and inhabiting other worlds, we can help ensure the long-term survival and advancement of our species. How cool is that?Of course, becoming an astronaut isn't easy. I know I'll have to study harder than ever before, get excellent grades, attend a top university, and be in absolute peak physical and mental condition. The training is said to be incredibly difficult and demanding. But I'm up for the challenge! With hard work, determination, and an unwavering commitment to pursuing my passion, I'm confident I can make it. Maybe I'll even get to be one of the first humans to set foot on Mars someday – now that would really be out of this world!I realize that the odds of actually becoming an astronaut are pretty slim. There's a lot of competition, and only a small number get selected for each astronaut class. But I don't let that discourage me at all. I'm going to give it my absolute best shot, squeezing every last drop out of my potential. And who knows? If the astronaut thing doesn't work out, there are so many other fascinating space-related careers I'd love to pursue – like being an astrophysicist, aerospace engineer, planet hunter, you name it. As long as I'm involved somehow in exploring and understanding the great cosmic frontier, I'll be doing what I love.To those of you who maybe don't understand the appeal of space or think becoming an astronaut is a silly dream, I'd just say this: Don't let go of those big, daring ambitions that set your heart on fire. It doesn't matter if others don't share or approve of your passion. If you can dream it, you can achieve it through hard work and perseverance. We're so fortunate to be living in an age of such incredible innovation and advancement in space travel. The universe is an astounding, mind-boggling place, and I can't wait to venture out and unravel more of its wondrous mysteries.So get ready, world – a future astronaut is coming! I'm going to keep pursuing my cosmic dream with all my heart and soul. To the moon? Been there, got the t-shirt. On to Mars, asteroids,Jupiter's moons, and beyond. The universe has so much to explore and I've got the burning ambition to be one of its great ambassadors and adventurers. Count on it!篇4My Dream to Become an AstronautHi there! My name is Jessica and I'm 10 years old. I'm in 5th grade and I love science, especially learning about outer space. For as long as I can remember, I've dreamed of becoming an astronaut when I grow up! I think it would be the coolest job ever.I can't get enough of learning about the planets, stars, galaxies, and everything else up in the sky. In science class, I always get super excited when we talk about space. My favorite planet is Saturn because of its cool rings. I have a big poster of the solar system on my bedroom wall so I can look at it every night before I go to bed.Did you know that astronauts have to go through years and years of tough training before they can go up into space? They have to take tons of classes on math, science, engineering, and even learn how to fly jets! They also have to exercise like crazy to get super strong and be able to handle the extreme conditionsof spaceflight. I've started doing push-ups and sit-ups every morning to get in shape!Living and working in space seems both amazing and terrifying at the same time. On one hand, you get to float around in zero gravity, look down at the entire Earth below you, and do science experiments that wouldn't be possible anywhere else. But on the other hand, you're traveling at thousands of miles per hour, dealing with extreme temperatures, and if something goes wrong, you're risking your life! I try not to think about that scary part too much though.I really admire all the brave astronauts who have explored space throughout history. Learning about people like Neil Armstrong, Sally Ride, and Yuri Gagarin is so inspiring. They showed that ordinary people can achieve extraordinary things through hard work and bravery. My biggest heroes are definitely the astronauts who walked on the Moon during the Apollo missions. Can you imagine how mind-blowing that must have been?!If I become an astronaut someday, I really hope I get to walk on the Moon or maybe even Mars! That would be a dream come true. I'd love to see what it's like on another world with my own eyes. I'd take tons of samples and do all kinds of experiments tolearn more about alien environments. Who knows what kind of new discoveries could be made?Of course, a big part of being an astronaut is learning to operate and repair the spacecraft you'll be flying in. I'm not exactly a mechanic or engineer yet, but I love building model rockets and rovers to practice those skills. Last summer, I went to Space Camp where I got to experience what it's like to live and work in a mock space station. It was a taste of the real thing!I know becoming an astronaut won't be easy. There are so many smart kids who dream of the same thing. But I'm going to study really hard, get great grades, and never stop working towards my goal. With enough perseverance, I'm confident I can make it! Maybe you'll see me on a rocket heading to the Moon or Mars in 20 years or so. Wish me luck!篇5My Dream of Becoming an AstronautHi there! My name is Alex and I'm 10 years old. I love learning about science, math, and exploring the great outdoors. But you know what really gets me excited? Space! The planets, stars, black holes, and galaxies far far away. It's all just so cooland amazing. That's why I've decided that when I grow up, I want to be an astronaut!Can you imagine what it would be like to leave Earth behind and travel amongst the stars? To look back at our beautiful blue and green planet floating in the vast darkness? I get chills just thinking about it. I would give anything to experience the incredible adventure of spaceflight.Astronauts get to do such amazing things that most people only dream of. Like walking in space during a spacewalk outside the International Space Station! They get to put on a special spacesuit and float around while repairing equipment or conducting experiments. How awesome is that? Just the thought of drifting weightless above our planet gives me butterflies.And can you imagine the feeling of blasting off in a powerful rocket? Strapped into your seat, the engines roar to life, and you feel the intense acceleration as you punch through the atmosphere into the inky blackness. No words can describe what that must feel like. I'm sure it's a little scary too, but astronauts are super brave!Once in space, astronauts get to live and work aboard the International Space Station, a brilliant laboratory about the size of a football field. They conduct all kinds of cool scienceexperiments testing out new technologies. But it's not all work - part of an astronaut's job is taking photos and videos of our home planet. I bet the view of the oceans, clouds, and city lights at night are breathtaking.Exploring other worlds has to be the best part though. Like when the astronauts landed on the Moon during the Apollo missions! Think of being the first to set foot on another celestial body. Bouncing around in low gravity, looking up at the Earth in the black sky. The adventures and discoveries must have been out of this world (literally!).That's why I dream of traveling even farther one day - to Mars! Can you picture it? The first human stepping out onto the reddish brown soil of an alien planet? Using robots to extract samples and search for signs of ancient life? Building a base to stay for months as we prepare for future exploration deeper into our solar system? I get so excited just imagining it all.Of course, becoming an astronaut won't be easy. It takes many years of hard work and dedication. I'll need to do very well in school, especially in subjects like math, science, and engineering. Astronauts have to be incredibly smart to operate all the complex equipment and technology involved in spaceflight.I'll also have to become an expert at activities like scuba diving, piloting aircraft, and doing extreme sports. That's because astronauts need excellent physical strength, courage and leadership abilities. You have to be in top condition to handle the enormous forces involved in launching off our planet!But I'm ready to study and train as hard as I can to pursue my dream. The challenges just make me more excited to try! I've already started learning Russian so I can talk to astronauts from around the world. Maybe I'll get to live and work in space one day with astronauts from Russia, Europe, Canada, Japan and other space nations.My absolute biggest goal is to be one of the first human explorers on Mars. Can you imagine? Setting foot where no human has gone before? Looking up at the rusty red sky and distant sun? Searching for signs of life。