Astronomy:the science of the stars The universe is made up of stars, planets, and other matter scattered throughout space. The Milky Way is a large spiral galaxy（螺旋星系） measuring about 100,000 light-years across. It is about 14 billion years old and takes 225 million years or so to rotate（旋转） once. Like all spirals, it contains plenty of gas and dust, from which new stars are formed. The dense nucleus（核心） is the oldest part and has no gas left for new star. The Solar system 1.Mercury(水星) 2.Venus(金星) 3.Earth(地球) 4.Mars（火星） 7.Uranus（天王星） 5.Jupiter（木星） 8.Neptune（海王星） 6.Saturn（土星） 9.Pluto（冥王星） Our solar system is made up of the sun and the objects that orbit it. These include the nine planets (and probably more than nine) and their moons, as well as asteroids（小行星）, comets, and meteors（流星）. The sun is the nearest star to the earth. It is a globe of hot gas, mostly hydrogen（.氢）, and lies at the center of our solar system. It contains no solid material. Stars are large balls of hot gas that produce light and heat through nuclear reactions. Our Sun is an average yellow star, but seems bright because it is so close. Mercury The Roman god of merchants and travellers Venus The Roman goddess of love Mars The Roman god of war Jupiter The king of the Roman gods Saturn The Roman god of seeds and sowing Uranus The Greek god of the sky Neptune The Roman god of the sea Pluto The Roman god of the dead Stars are large balls of hot gas that produce light and heat through nuclear reactions. Our Sun is an average yellow star, but seems bright because it is so close. Planets are the largest objects that circle around the stars. They may be rocky, like the earth, or made mostly of gas and liquid, like Jupiter. The word planet is Greek for "wanderer." The name comes from the way planets appear to move against the stars over time. It is thought that the planets formed at about the same time as the sun. As the original cloud of gas and dust collapsed to for the sun, some matter was spun out into a flattened disk. Over several million years, the dust and gas gathered together to form the planets and moons. Denser rocks gathered near the sun and lighter gases farther out. Our planet, the earth, is a large ball of rocks and metals covered with water and soil. It belongs to a group of nine planets that move around a star called the sun. It is surrounded by a blanket of gases called the atmosphere, has one moon, and as far as we know, is the only planet that supports life. NASA’s Mars detector（探测器）,Opportunity, succeeded in finding signs that water once existed on the planet. Opportunity landed on Mars in January. Scientists now believe that the planet could once have supported life.“Although we still can’t say that life could have existed in this environment, it is now certain that there was water on Mars,” said one of the scientists working on the Mars mission.（任务） How Life Began on the Earth Discussion: 1.Life is a mystery to our beings.Scientists study the origin of life by exploding space. Do you really think space fights are meaningful? Discuss the advantages and disadvantages of space flights. 2.Why is the earth the only one of all the planets on which life can survive? Has life started in other stars except on the earth? Read“How Life Began on the Earth”,then answer the following questions: 1. What’s the main idea of the text? Main idea: How life begin on the earth 2. How many parts can the text be divided into? What’s the main idea for each part? Two parts: Part1(para1):Water made it possible for life to begin to develop. Part2(para2,3,4): The development of living things. Read Part1 and answer questions: 1.How did water come into being on the earth? The explosion of the earth produced water vapour, which turn into water when the earth cooled down. 2.What’s the significance of the presence of water on the earth? It allowed the earth to dissolve harmful gases into oceans and seas. Read Part2 and answer questions: 1.Why were mammals different from dinosaurs? Because they produce their young from within their bodies. 2.Fill in the diagram: Small plants in water 1 3 6 2 4 5 7 8 9 2.shellfish and all sorts of fish 3. Green plants on land 4.insects(on land) 5.amphibian on land in water 6.forests 7.reptiles on land 8. Dinosaurs on land 9.mammals on land Read“How Life Began on the Earth”,fill in the diagram of life’s origins and process: Harmful gases Insects Amphibians Reptiles Dinosaurs Mammals including The human beings 3_____________ 1.water 2.land animals Plants in the seas Land plants 1. The Big Bang is the term used to describe a huge explosion that scientists believe happened around 15 billion years ago, creating our universe. Nobody knows what caused the Big Bang, since we cannot look back to a time before it. But just after the event, the universe is believed to have been a knot of tightly packed particles only about the size of a pea. Its temperature was ten thousand trillion, trillion degree Celsius. Homework: discussion: 1.Why is the presence of plants important for the development of life? 2.Is the earth getting warmer each year? If so, what effects will this have? What’s the “green house effect,” which some scientists say might destroy our plant? Will the burning of coal, oil, and natural gas cause the earth to become a dead planet like Venus? Goodbye!