天文学chapter12
自然科学公共选修课程——科学基础
自然科学公共选修课程——科学基础天文学导论 (278)物理学思想史与自然哲学 (280)等离子体科学和应用 (282)太空之旅 (284)创新与发明 (286)中国古代冶铸技术 (287)电影中的科学理念探讨 (289)思维能力与工程制图 (290)激光与现代生活概论 (293)营养化学 (295)美容化学 (297)《天文学导论》课程教学大纲一、课程名称天文学导论Introduction to Astronomy二、课程编码1405961三、学时与学分32/2四、先修课程无五、课程教学目标本课程为非天文专业的理工科或文科学生普及天文学知识而开设。
内容包括宇宙概貌，太阳系，九大行星，地球，月球，日蚀，月蚀的形成原因，恒星的形成，演化与死亡的规律。
致密星如中子星和黑洞的特征，星系的概念以及宇宙大爆炸学说等天文学基础知识。
讲授采用双语教学，配合大量多媒体精采图片以及天文学科普电影资料，以形象描述为主，基本上不用数学公式。
这样既可以去除学生的畏难情绪，又可以激发学生探索宇宙奥秘的兴趣，使他们感到确有收获。
六、适用学科专业全校各专业七、基本教学内容与学时安排Chapter 1 The universe at different scales (宇宙的不同尺度) （1学时）Chapter 2 The earth and the sky (地球和天空) （2学时）Chapter 3 Lunar phases, tides and eclipses (月相, 潮汐和蚀) （2学时）Chapter 4 The origin of modern astronomy (现代天文学的起源) （2学时）Chapter 5 Theory of motion and gravitation (运动理论和引力) （2学时）Chapter 6 Relativity (相对论) （2学时）Chapter 7 The solar system (太阳系) （2学时）Chapter 8 Measuring stars (测量恒星) （2学时）Chapter 9 The sun (太阳) （2学时）Chapter 10 The formation of stars (恒星的形成) （2学时）Chapter 11 Stellar evolution (恒星的演化) （2学时）Chapter 12 The deaths of stars (恒星的死亡) （2学时）Chapter 13 Neutron stars (中子星) （2学时）Chapter 14 Black holes (黑洞) （2学时）Chapter 15 Galaxies (星系) （1学时）Chapter 16 Cosmology (宇宙学) （1学时）附录A Electromagnetic radiation (电磁辐射) （0.5学时）附录B Atoms (原子) （0.5学时）复习（2学时）八、教材及参考书根据原版教材的简写版本编写，学生采用该教材的影印本278原版教材: Astronomy—The Solar System and BeyondAuthor: Michael A. Seeds (Joseph R. Grundy Observatory, Franklin and Marshall College) Press: Wadsworth Publishing Company (1998)天文爱好者杂志电影资料: 天文百科大全(York Films of England)第一集: 太阳系的诞生; 太阳, 水星, 金星, 地球, 月球;第二集: 银河系, 哈勃太空望远镜, 星系, 类星体, 大爆炸宇宙学, 黑洞, 暗物质;第三集: 观星史, 食与极光, 小行星, 宇宙辐射, 生命的探索第四集: 人造卫星, 太空先驱, 太空生活, 太空探测, 太空站;第五集: 火星, 木星, 土星, 天王星与海王星, 冥王星与彗星.电影资料: 美国《太空探索》系列第一集: 阿波罗登月计划;第二集: 人类太空探索的历史;第三集: 探索太阳系第四集: 走进宇航员世界;第五集: 美国太空发展四十年;第六集: 神秘火星的过去,现在和未来九、考核方式书面考试, 开卷, 英文试题(问答题), 可以用中文或者英文答题279《物理学思想史与自然哲学》课程教学大纲一、课程名称物理学思想史与自然哲学History of Physics Thoughts & Nature Phyilosophy二、课程编码1405991三、学时与学分24/1.5四、先修课程无五、课程教学目标（一）使学生从物理学史的角度来了解人类人探索自然的历程；（二）使学生了解哲学对科学发展怎样起着高屋建瓴的作用；（三）通过对物理学史上重要理论提出背景的讲解，告诉学生伟大的科学家们是怎样从平凡的现象中发现突破口，而做出重要的发现，使学生们从中受到启发，学会用新的、敏感的眼光去看待周围的事物，做一个科学上的有心人。
天文算法_―_译著：许剑伟概要
天文算法译著—许剑伟和他的译友第 1章注释与提示第 2章关于精度第 3章插值第 4章曲线拟合第 5章迭代第 6章排序第 7章儒略日第 8章复活节日期第 9章力学时和世界时第10章地球形状第11章恒星时与格林尼治时间第12章坐标变换第13章视差角第14章升、中天、降第15章大气折射第16章角度差第17章行星会合第18章在一条直线上的天体第19章包含三个天体的最小圆第20章岁差第21章章动及黄赤交角第22章恒星视差第23章轨道要素在不同坐标中的转换第24章太阳位置计算第25章太阳的直角坐标第26章分点和至点第27章时差第28章日面计算第29章开普勒方程第30章行星轨道要素第31章行星位置第32章椭圆运动第33章抛物线运动第34章准抛物线第35章一些行星现象的计算第36章冥王星第37章行星的近点和远点第38章经过交点第39章视差修正第40章行星圆面被照亮的比例及星等第41章火星物理表面星历计算(未译) 第42章木星物理表面星历计算(未译) 第43章木星的卫星位置(未译)第44章土星环(未译)第45章月球位置第46章月面的亮区第47章月相第48章月亮的近地点的远地点第49章月亮的升降交点第50章月亮的最大赤纬第51章月面计算第52章日月食第53章日月行星的视半径第54章恒星的星等第55章双星第56章日晷的计算备注译者说明原著《天文算法》天文算法天文算法 (1)前言 (1)第一章注释与提示 (1)第二章关于精度 (7)第三章插值 (16)第四章曲线拟合 (29)第五章迭代 (40)第六章排序 (47)第七章儒略日 (51)第八章复活节日期 (58)第九章力学时和世界时 (61)第十章地球形状 (65)第十一章恒星时与格林尼治时间 (70)第十二章坐标变换 (75)第十三章视差角 (80)第十四章天体的升、中天、降 (83)第十五章大气折射 (87)第十六章角度差 (89)第十七章行星会合 (97)第十八章在一条直线上的天体 (99)第十九章包含三个天体的最小圆 (101)第二十章岁差 (104)第二十一章章动及黄赤交角 (112)第二十二章恒星视差 (116)第二十三章轨道要素在不同坐标中的转换 (125)第二十四章太阳位置计算 (129)第二十五章太阳的直角坐标 (137)第二十六章分点和至点 (143)第二十七章时差 (148)第二十八章日面计算 (153)第二十九章开普勒方程 (157)第三十章行星的轨道要素 (172)第三十一章行星位置 (175)第三十二章椭圆运动 (178)第三十三章抛物线运动 (193)第三十四章准抛物线 (197)第三十五章一些行星现象的计算 (201)第三十六章冥王星 (211)第三十七章行星的近点和远点 (215)第三十八章经过交点 (221)第三十九章视差修正 (224)第四十章行星圆面被照亮的比例及星等 (230)第四十一章火星物理表面星历计算(未译) (234)第四十二章木星物理表面星历计算(未译) (234)第四十三章木星的卫星位置(未译) (234)第四十四章土星环(未译) (234)第四十五章月球位置 (235)第四十六章月面被照亮部分 (243)第四十七章月相 (246)第四十八章月亮的近地点和远地点 (252)第四十九章月亮的升降交点 (259)第五十章月亮的最大赤纬 (261)第五十一章月面计算 (265)第五十二章日月食 (273)第五十三章日月行星的视半径 (284)第五十四章恒星的星等 (286)第五十五章双星 (289)后记 (1)前言十分诚恳地感谢许剑伟和他的译友！在此我作一个拱手。
数学天文学原文与翻译
Mathematical Astronomy1.A brief history of cosmologyFour thousand years ago the Babylonians were skilled astronomers who were able to predict the apparent motions of the moon and the stars and the planets and the Sun upon the sky, and could even predict eclipses. But it was the Ancient Greeks who were the first to build a cosmological model within which to interpret these motions. In the fourth century BC, they developed the idea that the stars were fixed on a celestial sphere which rotated about the spherical Earth every 24 hours, and the planets, the Sun and the Moon, moved in the ether between the Earth and the stars. This model was further developed in the following centuries, culminating in the second century AD with Ptolemy's great system. Perfect motion should be in circles, so the stars and planets, being heavenly objects, moved in circles. However, to account for the complicated motion of the planets, which appear to periodically loop back upon themselves, epicycles had to be introduced so that the planets moved in circles upon circles about the fixed Earth.Despite its complicated structure, Ptolemy produced a model so successful at reproducing the apparent motion of the planets that when, in the sixteenth century, Copernicus proposed a heliocentric system, he could not match the accuracy of Ptolemy's Earth-centred system. Copernicus constructed a model where the Earth rotated and, together with the other planets, moved in a circular orbit about the Sun. But the observational evidence of the time favoured the Ptolemaic system!There were other practical reasons why many astronomers of the time rejected the Copernican notion that the Earth orbited the Sun. Tycho Brahe was the greatest astronomer of his the sixteenth century. He realised that if the Earth was moving about the Sun, then the relative positions of the stars should change as viewed from different parts of the Earth's orbit. But there was no evidence of this shift, called parallax. Either the Earth was fixed, or else the stars would have to be fantastically far away.It was only with the aid of the newly-invented telescope in the early seventeenth century that Galileo could deal a fatal blow to the notion that the Earth was at the centre of the Universe. He discovered moons orbiting the planet Jupiter. And if moons could orbit another planet, why could not the planets orbit the Sun?At the same time, Tycho Brahe's assistant Kepler discovered the key to building a heliocentric model. The planets moved in ellipses, not perfect circles, about the Sun. Newton later showed that elliptical motion could be explained by his inverse-square law for the gravitational force.But the absence of any observable parallax in the apparent positions of the stars as the Earth rotated the Sun, then implied that the stars must be at a huge distance from the Sun. The cosmos seemed to be a vast sea of stars. With the aid of his telescope, Galileo could resolve thousands of new stars which were invisible to the naked eye. Newton concluded that the Universe must be an infinite and eternal sea of stars, each much like our own Sun.It was not until in the nineteenth century that the astronomer and mathematicianBessel finally measured the distance to the stars by parallax. The nearest star (other than the Sun) turned out to be about 25 million, million miles away! (By contrast the Sun is a mere 93 million miles away from the Earth.)Most of the stars we can see are contained in the Milky Way - the bright band of stars that stretches across our night sky. Kant and others proposed that our Milky Way was in fact a lens shaped "island universe'' or galaxy, and that beyond our own Milky Way must be other galaxies.As well as stars and planets, astronomers had noted fuzzy patches of light on the night sky, which they called nebulae. Some astronomers thought these could be distant galaxies. It was only in the 1920's that the American astronomer Hubble established that some of these nebulae were indeed distant galaxies comparable in size to our own Milky Way.Hubble also made the remarkable discovery that these galaxies seemed to be moving away from us, with a speed proportional to their distance from us. It was soon realised that this had a very natural explanation in terms of Einstein's recently discovered General Theory of Relativity: our Universe is expanding!In fact, Einstein might have predicted that the Universe is expanding after he first proposed his theory in 1915. Matter tends to fall together under gravity so it was impossible to have a static universe. However, Einstein realised he could introduce a arbitrary constant into his mathematical equations, which could balance the gravitational force and keep the galaxies apart. This became known as the cosmological constant. After it was discovered that the Universe wa s actually expanding, Einstein declared that introducing the cosmological constant was the greatest blunder of his life!The Russian mathematician and meteorologist Friedmann had realised in 1917 that Einstein equations could describe an expanding universe. This solution implied that the Universe had been born at one moment, about ten thousand million years ago in the past and the galaxies were still travelling away from us after that initial burst. All the matter, indeed the Universe itself, was created at just one instant. The British astronomer Fred Hoyle dismissively called it the "Big Bang'', and the name stuck. There was a rival model, called the Steady State theory - advocated by Bondi, Gold and Hoyle - developed to explain the expansion of the Universe. This required the continuous creation of matter to produce new galaxies as the universe expanded, ensuring that the Universe could be expanding, but still unchanging in time.For many years it seemed a purely academic point, whether the universe was eternal and unchanging, or had only existed for a finite length of time. But a decisive blow was dealt to the Steady State model when in 1965 Penzias and Wilson discovered a cosmic microwave background radiation. This was interpreted as the faint afterglo w of the intense radiation of a Hot Big Bang, which had been predicted by Alpher and Hermann back in 1949.Following on from earlier work by Gamow, Alpher and Herman in the 1940's, theorists calculated the relative abundances of the elements hydrogen and helium that might be produced in a Hot Big Bang and found it was in good agreement with the observations. When the abundance of other light elements was calculated these toowere consistent with the values observed.Since the 1970's almost all cosmologists have come to accept the Hot Big Bang model and have begun asking more specific, but still fundamental, questions about our Universe. How did the galaxies and clusters of galaxies that we observe today form out of the primordial expansion. What is most of the matter in the Universe made of? How do we know that there are not black holes or some kind of dark matter out there which does not shine like stars? General relativity tells us that matter curves space-time, so what shape is the Universe? Is there a cosmological constant after all? We are only beginning to find answers to some of these questions. The cosmic microwave background radiation plays a key role as it gives us a picture of the universe as it was only a hundred thousand years after the Big Bang. It turns out to be so remarkably uniform, that it was only in 1992 that NASA's Cosmic Background Explorer satellite detected the first anisotropies in this background radiation. There are slight fluctuations in the temperature of the radiation, about one part in a hundred thousand, which may be the seeds from which galaxies formed.Since the early 1980's there has been an explosion of interest in the physics of the early universe. New technology and satellite experiments, such as the Hubble Space Telescope, have brought us an ever improving picture of our Universe, inspiring theorists to produce ever more daring models, drawing upon the latest ideas in relativity and particle physics.2.Greek astronomyToday the study of astronomy requires a deep understanding of mathematics and physics. It is important to realise that Greek astronomy (we are interested in the topic during the 1000 years between 700 BC and 300 AD) did not involve physics. Indeed, as Pannekoek points out in [7], a Greek astronomer aimed only to describe the heavens while a Greek physicist sought out physical truth. Mathematics provided the means of description, so astronomy during the 1000 years that interest us in this article was one of the branches of mathematics.The Greeks began to think of philosophy from the time of Thales in about 600 BC. Thales himself, although famed for his prediction of an eclipse, probably had little knowledge of astronomy, yet he brought back from Egypt knowledge of mathematics into the Greek world and possibly also some knowledge of Babylonian astronomy. It is reasonable to begin by looking at what 'astronomy' was in Greece around this time. However we begin by looking further back than this to around 700 BC.Basically at this time astronomy was all to do with time keeping. It is natural that astronomical events such as the day would make a natural period of time and likewise the periodic phases of the moon make the next natural time span. Indeed these provided the basic methods of time keeping around the period of 700 BC yet, of course, another important period of time, the year, was not easy to determine in terms of months. Y et a knowledge of the approximate length of the year was vital for food production and so schemes had to be devised. Farmers at this time would base their planting strategies on the rising and setting of the constellations, that is the times when certain constellations would first become visible before sunrise or were last visible after sunset.Hesiad, one of the earliest Greek poets, often called the "father of Greek didactic poetry" wrote around 700 BC. Two of his complete epics have survived, the one relevant to us here is Works and Days describing peasant life. In this work Hesiad writes that (see [5], also [1] and [7]):-... when the Pleiades rise it is time to use the sickle, but the plough when they are setting; 40 days they stay away from heaven; when Arcturus ascends from the sea and, rising in the evening, remain visible for the entire night, the grapes must be pruned; but when Orion and Sirius come in the middle of heaven and the rosy fingered Eos sees Arcturus, the grapes must be picked; when the Pleiades, the Hyades, and Orion are setting, then mind the plough; when the Pleiades, fleeing Orion, plunge into the dark sea, storms may be expected; 50 days after the sun's turning is the right time for man to navigate; when Orion appears, Demeter's gift has to be brought to the well-smoothed threshing floor.For many hundreds of years astronomers would write works on such rising and setting of constellations indicating that the type of advice given by Hesiad continued to be used.An early time scale based on 12 months of 30 days did not work well since the moon rapidly gets out of phase with a 30 day month. So by 600 BC this had bee n replaced by a year of 6 'full' months of 30 days and 6 'empty' months of 29 days. This improvement in keeping the moon in phase with the month had the unfortunate effect of taking the year even further out of phase with the period of the recurring seasons. About the same time as Thales was making the first steps in philosophy, Solon, a statesman in Athens who became known as one of the Seven Wise Men of Greece, introduced an improved calendar.Solon's calendar was based on a two yearly cycle. There were 13 months of 30 days and 12 months of 29 days in each period of two years so this gave a year of about 369 days and a month of 291/2days. However, the Greeks relied mainly on the moon as their time-keeper and frequent adjustments to the calendar were necessary to keep it in phase with the moon and the seasons. Astronomy was clearly a subject of major practical importance in sorting out the mess of these calendars and so observations began to be made to enable better schemes to be devised.Pythagoras, around 500 BC, made a number of important advances in astronomy. He recognised that the earth was a sphere, probably more because he believed that a sphere was the most perfect shape than for genuine scientific reasons. He also recognised that the orbit of the Moon was inclined to the equator of the Earth and he was one of the first to realise that V enus as an evening star was the same planet as V enus as a morning star. There is a pleasing appeal to observational evidence in these discoveries, but Pythagoras had a philosophy based on mathematical 'perfection' which tended to work against a proper scientific approach. On the other side there is an important idea in the Pythagorean philosophy which had a lasting impact, namely the idea that all complex phenomena must reduce to simple ones. One should not underestimate the importance of this idea which has proved so powerful throughout the development of science, being a fundamental driving force to the great scientists such as Newton and particularly Einstein.Around 450 BC Oenopides is said to have discovered the ecliptic made an angle of 24° with the equator, which was accepted in Greece until refined by Eratosthenes in around 250 BC. Some scholars accept that he discovered that the ecliptic was at an angle but doubt that he measured the angle. Whether he learnt of the 12 signs of the zodiac from scholars in Mesopotamia or whether his discoveries were independent Greek discoveries is unknown. Oenopides is also credited with suggesting a calendar involving a 59 year cycle with 730 months. Other schemes proposed were 8 year cycles, with extra months in three of the eight years and there is evidence that this scheme was adopted.About the same time as Oenopides proposed his 59 year cycle, Philolaus who was a Pythagorean, also proposed a 59 year cycle based on 729 months. This seemed to owe more to the numerology of the Pythagoreans than to astronomy since 729 is 272, 27 being the Pythagorean number for the moon, while it is also 93, 9 being the Pythagorean number associated with the earth. Philolaus is also famed as the first person who we know to propose that the earth moves. He did not have it orbiting the sun, however, but rather all the heavenly bodies went in circles round a central fire which one could never see since there was a counter earth between the earth and the fire. This model, certainly not suggested by any observational evidence, is more likely to have been proposed so that there were 10 heavenly bodies, for 10 was the most perfect of all numbers to the Pythagoreans.Meton, in 432 BC, introduced a calendar based on a 19 year cycle but again this is similar to one devised in Mesopotamia some years earlier. Meton worked in Athens with another astronomer Euctemon, and they made a series of observations of the solstices (the points at which the sun is at greatest distance from the equator) in order to determine the length of the tropical year. Again we do not know if the 19 year cycle was an independent discovery or whether Greek advances were still based on earlier advances in Mesopotamia. Meton's calendar never seems to have been adopted in practice but his observations proved extremely useful to later Greek astronomers such as Hipparchus and Ptolemy.That Meton was famous and widely known is seen from the play Birds written by Aristopenes in about 414 BC. Two characters are speaking, one is Meton [see D Barrett (trs.), Aristophanes, Birds (London, 1978)]:-Meton: I propose to survey the air for you: it will have to be marked out in acres. Peisthetaerus: Good lord, who do you think you are?Meton: Who am I? Why Meton. THE Meton. Famous throughout the Hellenic world - you must have heard of my hydraulic clock at Colonus?Meton and Euctemon are associated with another important astronomical invention of the time, namely a parapegma. A parapegma was a stone tablet with movable pegs and an inscription to indicate the approximate correspondence between, for example, the rising of a particular star and the civil date. Because the calendar had to be changed regularly to keep the civil calendar in phase with the astronomical one, the parapegma had movable pegs which could be adjusted as necessary. A parapegma soon also contained meteorological forecasts associated with the risings and settings of the stars and not only were stone parapegma constructed but also ones on papyri.Meton and Euctemon are usually acknowledged as the inventors of parapegmata and certainly many later astronomers compiled the data nessary for their construction. There is evidence for other observational work being undertaken around this time, for Vitruvius claims that Democritus of Abdera, famed for his atomic theory, devised a star catalogue. We have no knowledge of the form this catalogue took but Democritus may well have described the major constellations in some way.The beginning of the 4th century BC was the time that Plato began his teachings and his writing was to have a major influence of Greek thought. As far as astronomy is concerned Plato had a negative effect, for although he mentions the topic many times, no dialogue is devoted to astronomy. Worse still, Plato did not believe in astronomy as a practical subject, and condemned as lowering the spirit the actual observation of the heavenly bodies. Plato only believed in astronomy to the extent that it encouraged the study of mathematics and suggested beautiful geometrical theories.Perhaps we should digress for a moment to think about how the ideas of philosophy which were being developed by Plato and others affected the development of astronomy. Neugebauer [6] feels that philosophy had a detrimental affect:-I see no need for considering Greek philosophy as an early stage in the development of science ... One need only read the gibberish of Proclus's introduction to his huge commentary on Book I of Euclid's Elements to get a vivid picture of what would have become of science in the hands of philosophers. The real "Greek miracle" is the fact that a scientific methodology was developed, and survived, in spite of a widely admired dogmatic philosophy.Although there is some truth in what Neugebauer writes here, I [EFR] feel that he has overstated his case. It is true that philosophers came up with ideas about the universe which were not based on what we would call today the scientific method. However, the very fact that theories were proposed which could be shown to be false by making observations, must have provided a climate where the scientific approach could show its strength. Also the fact the philosophy taught that one should question all things, even "obvious" truths, was highly beneficial. Another important philosophical idea which had important consequences from the time of Pythagoras, and was emphasised by Plato, was that complex phenomena must be consequences of basic simple phenomena. As Theon of Smyrna expressed it, writing in the first century AD:-The changing aspects of the revolution of the planets is because, being fixed in their own circles or in their own shperes whose movements they follow, they are carried across the zodiac, just as Pythagoras had first understood it, by a regulated simple and equal revolution but which results by combination in a movement that appears variable and unequal.This led Theon to write:-It is natural and necessary that all the heavenly bodies have a uniform and regular movement.Perhaps the most telling argument against the above claim by Neugebauer is that our present idea of space-time, as developed from Einstein's theory of relativity, was suggested more by the basic philosophy of simplicity than by experimental evidence. The advances made not long after the time of Plato by Eudoxus, incorporating theidea of basic simplicity as expressed in Pythagorean and Platonic philosophy, were made by an outstanding mathematician and astronomer. In fact Eudoxus marks the beginning of a new phase in Greek astronomy and must figure as one of a small number of remarkable innovators in astronomical thought. Eudoxus was the first to propose a model whereby the apparently complex motions of the heavenly bodies did indeed result from simple circular motion. He built an observatory on Cnidus and from there he observed the star Canopus. The star Canopus played an important role in early astronomy, for it is seen to set and rise in Cnidus yet one does no have to go much further north from there before it can never be seen. The observations made at Eudoxus's observatory in Cnidus, as well as those made at an observatory near Heliopolis, formed the basis of a book concerning the rising and setting of the constellations. Eudoxus, another who followed Pythagorean doctrines, proposed a beautiful mathematical theory of concentric spheres to describe the motion of the heavenly bodies. It is clear that Eudoxus thought of this as a mathematical theory, and did not believe in the spheres as physical objects.Although a beautiful mathematical theory, Eudoxus's model would not have stood the test of the simplest of observational data. Callippus, who was a pupil of Polemarchus himself a pupil of Eudoxus, refined this system as presented by Eudoxus. The reason that we have so much information about the spheres of Eudoxus and Callippus is that Aristotle accepted the theory, not not as a mathematical model as originally proposed, but rather as spheres which have physical reality. He discussed the interactions of one sphere on another, but there is no way that he could have had enough understanding of physics to get anywhere near describing the effects of such an interaction. Although in many areas Aristotle advocated a modern scientific approach and he collected data in a scientific way, this was unfortunately not the case in astronomy. As Berry writes [2]:- There are also in Aristotle's writings a number of astronomical speculations, founded on no solid evidence and of little value ... his original contributions are not comparable with his contributions to the mental and moral sciences, but are inferior in value to his work in other natural sciences ...As Berry goes on to say, this was very unfortunate for astronomy since the influence of the writings of Aristotle had an authority for many centuries which meant that astronomers had a harder battle than they might otherwise have had in getting the truth accepted.The next development which was absolutely necessary for progress in astronomy took place in geometry. Spherical geometry was developed by a number of mathematicians with an important text being written by Autolycus in Athens around 330 BC. Some claim that Autolycus based his work on spherical geometry On the Moving Sphere on an earlier work by Eudoxus. Whether or not this is the case there is no doubt that Autolycus was strongly influenced by the views of Eudoxus on astronomy. Like so many astronomers, Autolycus wrote a work On Risings and Settings which is a book on observational astronomy.After Autolycus the main place for major developments in astronomy seemed to move to Alexandria. There Euclid worked and wrote on geometry in general but also making an important contribution to spherical geometry. Euclid also wrotePhaenomena which is an elementary introduction to mathematical astronomy and gives results on the times stars in certain positions will rise and set.Aristarchus, Timocharis and Aristyllus were three astronomers who all worked at Alexandria and their lives certainly overlapped. Aristyllus was a pupil of Timocharis and in Maeyama [23] analyses 18 of their observations and shows that Timocharis observed around 290 BC while Aristyllus observed a generation later around 260 BC. He also reports an astounding accuracy of 5' for Aristyllus' observations. Maeyama writes [23]:- The order of accuracy is an essential measure for the development of natural sciences. accuracy is in fact more than the mere operation of measuring. Accuracy increases only by virtue of active measuring. There cannot exist a high order of observational accuracy which is not connected with a high order of observations. Hence my assumption is that there must have been abundant accurate observations of the fixed stars made at least at the epochs 300 BC - 250 BC in Alexandria. They must have disappeared in the fires which frequently raged there. Maeyama also points out that this is the period when the coordinate systems for giving stellar positions originated. Both the equatorial and the ecliptic systems appear at this time. But why were these observations being made? This is a difficult question to answer for on the face of it there seems little point in the astronomers of Alexandria striving for observational accuracy at this time. In [34] van der Waerden makes an interesting suggestion related to the other important astronomer who worked in Alexandria around this time, namely Aristarchus.We know that Aristarchus measured the ratio of the distances to the moon and to the sun and, although his methods could never yield accurate results, they did show that the sun was much further from the earth than was the moon. His results also showed that the sun was much larger than the earth, although again his measurements were very inaccurate. Some historians believe that this knowledge that the sun was the largest of the three bodies, earth, moon and sun, led him to propose his heliocentric theory. Certainly it is for this theory, as reported by Archimedes, that Aristarchus has achieved fame. His sun-centred universe found little favour with the Greeks, however, who continued to develop more and more sophisticated models based on an earth centred universe.Now Goldstein and Bowen in [16] attempt to answer the question of why Timocharis and Aristyllus made their accurate observations. These authors do not find a clear purpose for the observations, such as the marking of a globe. However van der Waerden in [34] suggests that the observations were made to determine the constants in the heliocentric theory of Aristarchus. Although this theory has strong attractions, and makes one want to believe in it, all the evidence suggests that Timocharis certainly began his observations some time before Aristarchus proposed his heliocentric universe.Goldstein and Bowen in [16] make other interesting suggestions. They believe that the observations of Timocharis and Aristyllus recorded the distance from the pole, and the distances between stars. They argued that the observations were made by means of an instrument similar to Heron's dioptra. These are interesting observations since the work of Timocharis and Aristyllus strongly influenced the most important of all of theGreek astronomers, namely Hipparchus, who made his major contribution about 100 years later. During these 100 years, however, there were a number of advances. Archimedes measured the apparent diameter of the sun and also is said to have designed a planetarium. Eratosthenes made important measurements of the size of the earth, accurately measured the angle of the ecliptic and improved the calendar. Apollonius used his geometric skills to mathematically develop the epicycle theory which would reach its full importance in the work of Ptolemy.The contributions of Hipparchus are the most important of all the ancient astronomers and it is fair to say that he made the most important contribution before that of Copernicus in the early sixteenth century. As Berry writes in [2]:- An immense advance in astronomy was made by Hipparchus, whom all competent critics have agreed to rank far above any other astronomers of the ancient world, and who must stand side by side with the greatest astronomers of all time.It is Hipparchus's approach to science that ranks him far above other ancient astronomers. His approach, based on data from accurate observations, is essentially modern in that he collected his data and then formed his theories to fit the observed facts. Most telling regarding his understanding of the scientific method is the fact that he proposed a theory of the motion of the sun and the moon yet he was not prepared to propose such a theory for the planets. He realised that his data was not sufficiently good or sufficiently plentiful to allow him to base a theory on it. However, he made observations to help his successors to develop such a theory. Delambre, in his famous work on the history of astronomy, writes:- When we consider all that Hipparchus invented or perfected, and reflect upon the number of his works and the mass of calculations which they imply, we must regard him as one of the most astonishing men of antiquity, and as the greatest of all in the sciences which are not purely speculative, and which require a combination of geometrical knowledge with a knowledge of phenomena, to be observed only by diligent attention and refined instruments. Although a great innovator, Hipparchus gained important understanding from the Babylonians. As Jones writes in [21]:- For Hipparchus, the availability of the Babylonian predictive methods was a boon.We will not describe the contributions of Hipparchus and Ptolemy in detail in this article since these are given fully in their biographies in our archive. Suffice to end this article with a quotation from [6]:- Alexandria in the second century AD saw the publication of Ptolemy's remarkable works, the 'Almagest' and the 'Handy Tables', the 'Geography', the 'Tetrabiblos', the 'Optics', the 'Harmonics', treatises on logic, on sundials, on stereographic projection, all masterfully written, products of one of the greatest scientific minds of all times. The eminence of these works, in particular the 'Almagest', had been evident already to Ptolemy's contemporaries. this caused an almost total obliteration of the prehistory of the Ptolemaic astronomy.Ptolemy had no successor. What is extant from the later Roman times is rather sad.....3.Mathematical discovery of planetsThe first planet to be discovered was Uranus by William and Caroline Herschel on 13 March 1781. It was discovered by the fact that it showed a disk when viewed through even a fairly low powered telescope. The only other planets which have been。
天文学基础知识
天文学基础知识简介:天文学是研究宇宙、星体、星系和宇宙现象的科学领域。
本文将介绍一些天文学的基础知识，包括天体的分类、太阳系的组成和星体运动的基本原理。
第一节：天体的分类天文学根据天体的性质和特征将其分类。
主要的天体包括星星、行星、卫星、恒星、星系和星云。
1. 星星星星是由氢气和其他元素通过核聚变反应产生能量的大型气体球体。
它们通过核反应产生的能量持续辐射和照亮宇宙。
2. 行星行星是围绕太阳或其他恒星运行的天体。
行星通常分为内行星（如地球、金星和火星）和外行星（如木星、土星和天王星）两类。
行星有自身的重力，并且能够固定轨道上运行。
3. 卫星卫星是围绕行星或其他天体运行的较小的天体。
例如，月球是围绕地球运行的卫星。
卫星有时也被称为“自然卫星”，以区分于人造卫星。
4. 恒星恒星是天空中明亮的点状物体，它们通过核聚变反应产生强烈的光和热。
恒星的大小和亮度不同，有些恒星比太阳还要大几百倍。
5. 星系星系是由恒星、气体、尘埃和其他物质组成的巨大结构。
银河系是我们所在的星系，它包含了数以千亿计的恒星。
6. 星云星云是由气体和尘埃组成的大型云状结构。
星云通常是恒星形成的地方。
有些星云非常庞大，可以观察到它们的光芒。
第二节：太阳系的组成太阳系是我们所在的星系，它由太阳、行星、卫星、小行星和彗星等天体组成。
1. 太阳太阳是太阳系的中心星体，它是一个巨大的恒星，占据太阳系中大部分的质量。
太阳通过核聚变反应产生能量，并向太阳系中的其他天体提供光和热。
2. 行星太阳系中有八个行星，按照距离太阳的远近可以分为内行星和外行星。
内行星是靠近太阳的行星，包括水金火球、金星、地球和火星。
外行星则包括木土天王冥。
3. 卫星太阳系中的行星都有自己的卫星。
例如，地球有一个卫星——月球。
卫星围绕行星运行，由于受到行星的引力影响，保持着稳定的轨道。
4. 小行星小行星是太阳系中未成为行星的天体。
它们主要分布在火星和木星之间，形成一个被称为小行星带的区域。
天文学教程pdf
天文学教程一、天文学基础1. 天文学的定义：天文学是研究宇宙中天体的学科，包括恒星、行星、星系、星云、星团、星系团等。
它旨在理解宇宙的结构、起源和演化。
2. 天文学的重要性：天文学对人类文明的发展有着深远的影响。
它不仅帮助我们认识宇宙，还推动了数学、物理学、化学等其他学科的发展。
3. 天文学的历史：从天文学发展的历程来看，可以划分为古代天文学、近代天文学和现代天文学三个阶段。
古代天文学以肉眼观测和简单的仪器为主，积累了大量的天文资料，并提出了许多有价值的理论。
近代天文学则以望远镜的发明和应用为标志，开始了对宇宙的更深入探索。
现代天文学则借助大型望远镜、卫星和空间探测器等高科技手段，对宇宙进行全方位的研究。
二、天体与天体系统1. 恒星：恒星是宇宙中最基本的天体之一，它们通过核聚变产生能量和光。
根据质量、温度和光谱等特征，恒星可以分为不同的类型，如O型星、B型星、A型星等。
恒星的生命周期包括主序阶段、红巨星阶段和白矮星阶段等。
2. 太阳系：太阳系是一个由太阳和围绕其旋转的行星、卫星、小行星、彗星等天体组成的天体系统。
太阳是太阳系的中心，它提供了太阳系内所有天体所需的光和热。
行星是太阳系中最大的天体之一，它们按照距离太阳的远近可以分为内行星和外行星。
3. 银河系：银河系是一个由数千亿颗恒星组成的巨大星系，它呈旋涡状结构，中心有一个巨大的黑洞。
我们的太阳就位于银河系的一条旋臂上。
4. 星系：宇宙中存在大量的星系，它们形态各异，大小不一。
根据形态和特征，星系可以分为椭圆星系、旋涡星系和不规则星系等类型。
星系之间的距离非常遥远，通常以数百万光年甚至数十亿光年计。
5. 星系团和超星系团：星系团是由数十个到数千个星系组成的巨大天体系统。
而超星系团则是由多个星系团组成的更大的天体系统。
这些巨大的天体系统在宇宙中形成了复杂的网络结构。
三、天文观测与仪器1. 肉眼观测：在古代，人们主要通过肉眼观测来认识天体。
他们观察太阳、月亮、行星和恒星等天体的位置和运动，并积累了丰富的天文资料。
天文学基础知识点详解
天文学基础知识点详解在我们日常生活中，我们总是被广袤的宇宙所吸引。
我们想要了解科学家们是如何研究天文学的，以及他们探索宇宙的奥秘。
在本文中，我们将详细讨论几个天文学的基础知识点，以帮助我们更好地理解宇宙的运行。
一、太阳系的结构太阳系是由太阳、行星、卫星、小行星带和彗星带等组成的巨大物质系统。
太阳是太阳系的中心，围绕太阳运行的是包括水星、金星、地球和火星在内的行星。
而行星的卫星也围绕行星自转。
此外，太阳系中还有一片较为稀疏的小天体区域，称为小行星带，以及远离太阳的彗星带，这些小行星和彗星的轨道也受到太阳的引力影响。
二、恒星与星系恒星是宇宙中的基本构建单元，由巨大的气体核心和被引力束缚在周围的等离子体组成。
恒星可以通过测量其亮度、颜色和光谱进行分类，其中最常见的恒星类型包括红矮星、黄矮星和蓝巨星。
恒星之间以银河系等大型星系的形式组织在一起。
星系是由庞大数量的恒星、行星、恒星附近的气体云和黑洞组成的。
银河系是我们所在的星系，它包含大约2000亿颗星星。
三、宇宙膨胀宇宙膨胀是现代天文学的一个重要理论，它基于观测到的宇宙中的星系在互相远离。
根据大爆炸理论，宇宙是在约137亿年前从一个极端高温高密度的初始状态膨胀而来的。
而事实上，宇宙膨胀并不意味着事物扩张到了宇宙中的某个地方，而是空间本身的膨胀。
四、黑洞和中子星黑洞是宇宙中最神秘的物体之一，它是一种密度极高、引力极强的天体。
黑洞的引力场非常强大，甚至连光都无法逃离，因此我们无法直接观测到黑洞。
中子星是由大质量恒星爆炸后残留下来的，它的质量非常庞大，但体积却非常小。
中子星由中子组成，这些中子被压缩得非常紧密，以至于它们之间的关系能够抵消自身引力。
五、星际物质星际物质是宇宙中广泛存在的物质，由气体和微尘组成。
这些星际物质形成了星际云，它们是新星形成的原材料。
星际云具有不同的密度和温度，当其中的一些地区足够密集时，就会形成新的恒星。
总结：天文学是人类对宇宙和天体的研究。
简明天文学教程第二版第十二章答案 余明主编
第十二章宇宙学1. 什么是宇宙？天文学的宇宙与哲学的宇宙有何区别？⑴对于宇宙的理解有天文学和哲学的概念。
天文学宇宙指的是科学宇宙，定义迄今为止观测所及的星系及星系总体。
时间上有起源，空间上有边界。
哲学宇宙指的是普通的、永恒的物质世界。
在时间上是无始无终的，在空间上是无边无际的。
⑵区别：①天文学上宇宙是人们观测所及的宇宙部分。
②哲学上的宇宙是无所不包的，所以天文学上的宇宙是无限宇宙的一部分。
2. 西方宇宙论的研究经历了哪些时期？20世纪以前的西方宇宙论可分四个发展时期。
第一个时期是启蒙时期，主要是远古时代关于宇宙的神话传说。
第二个时期是从公元前六世纪到公元一世纪，以至直到中世纪（15世纪）为止，古希腊，罗马在宇宙的本源和结构上曾出现过唯物论，唯心论两派的激烈斗争，此后西方进入中世纪，宇宙学沦入经院哲学的神学深渊，地心学主宰宇宙学。
第三时期是从十六世纪到十七世纪，十六世纪哥白尼倡导日心说，开始把宇宙学从神学中解放出来，到十七世纪，牛顿开辟了以力学方法研究宇宙学的新生途径，形成了经典宇宙学。
第四学期，十八世纪到十九世纪，自康德拉普拉斯的星云说问世以后，确立了天体演化学科，赫歇尔父子对恒星进行了大量的观测，把以前只局限于太阳系的研究扩大到银河系和河外星系，在此期间，已经有分光方法应用于天文学，这一时期的发展给现代宇宙的发展奠定了基础。
哈勃膨胀、微波背景辐射、轻元素的合成以及宇宙年龄的测量被认为是现代宇宙学的四大基石。
现代宇宙学包括密切联系的两个方面，即观测宇宙学和物理宇宙学。
前者侧重于发现大尺度的观测特征，后者侧重于研究宇宙的运动、动力学和物理学以及建立宇宙模型。
从地心说、日心学到无心学是人类认识宇宙的三个里程碑。
但宇宙的命运究竟如何？人类还没有把握。
宇宙的起源和演化是当代宇宙学的前沿课题。
3. 我国的宇宙论研究的发展过程怎样？中国是世界上古老文明的发源地之一，在天文学方面有着灿烂的历史，在天象记载、天文仪器制作和宇宙理论方面都留下了珍贵的记录。
天文学基础知识入门
天文学基础知识入门天文学基础知识入门天文学是研究天体和宇宙现象的科学，它涉及了对星体、行星、星系、宇宙膨胀等各个方面的研究。
本文将带您入门天文学的基础知识，包括宇宙的起源和演化、星体的分类、行星的形成以及天文观测等内容。
一、宇宙的起源和演化关于宇宙的起源和演化，科学家目前普遍接受的理论是大爆炸理论。
大爆炸理论认为，宇宙起源于约138亿年前的一次巨大爆炸，这个时刻被称为大爆炸。
在大爆炸之后，宇宙开始膨胀，物质不断扩散，星体和星系逐渐形成。
随着时间的推移，宇宙膨胀的速度逐渐加快，这被称为宇宙的加速膨胀。
关于宇宙加速膨胀的原因，科学家提出了暗能量的假设。
暗能量是一种未知的能量形式，它存在于宇宙的各个角落，并且对宇宙的膨胀有巨大的影响。
二、星体的分类星体是宇宙中的各种天体，包括恒星、行星、卫星、彗星等。
根据在宇宙中的位置和性质，星体可以分为不同的类型。
1. 恒星：恒星是宇宙中的光源，它们通过核聚变反应产生能量。
恒星的大小和质量不同，可以分为超巨星、巨星、主序星、白矮星和中子星等。
2. 行星：行星是围绕恒星运行的天体，它们不发光，依靠恒星的光来反射出自己的光。
行星可以分为地球类行星（内行星）和巨大气态行星（外行星）两大类。
3. 卫星：卫星是围绕行星或其他天体旋转的天体，例如月球是地球的卫星，木卫二是木星的卫星。
4. 彗星：彗星是由冰和岩石组成的天体，它们绕太阳运行，并在靠近太阳的时候释放出尾巴。
三、行星的形成行星的形成与恒星的形成有着密切关系。
根据目前的科学理论，行星形成的过程主要包括原行星盘的形成、凝聚和形成行星的过程。
首先，在恒星形成的过程中，原恒星云会形成一个巨大的盘状结构，称为原恒星盘。
原恒星盘主要由氢气、氦气和微尘组成。
接着，微尘颗粒在原恒星盘中逐渐聚集成更大的块状物质，这个过程被称为凝聚。
当这些块状物质增长到一定的大小时，它们之间的引力相互作用使它们逐渐聚集成行星。
最后，行星形成后会继续围绕恒星运行，成为行星系统的一部分。
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At masses below 0.08 Msun, stellar progenitors do not get hot enough to ignite thermonuclear
fusion.
Brown Dwarfs
Brown Dwarfs
Hard to find because they are very faint and cool; emit mostly in the infrared.
III. Evidence of Evolution: Star Clusters A. Observing Star Clusters B. The Evolution of Star Clusters
IV. Evidence of Evolution: Variable Stars A. Cepheid and RR Lyrae Variable Stars B. Pulsating Stars C. Period Changes in Variable Stars
Development of Carbon-Oxygen
Core
Helium ignition in the core
Red giant
Expansion to red giant
Main Sequence
Fusion Into Heavier Elements
Fusion into heavier elements than C, O requires very high temperatures; occurs only in very massive stars (more than 8 solar
4 H → He He
H-burning shell keeps dumping He
onto the core.
He-core gets denser and hotter until the next stage of nuclear burning can begin in
the core:
He fusion through the
“Triple-Alpha Process”
4He + 4He 8Be + g
8Be + 4He 12C + g
Red Giant Evolution (5 solar-mass star)
Helium in the core exhausted;
development of He-burning shell
Stellar Models
The structure and evolution of a star is determined by the laws of
• Hydrostatic equilibrium • Energy transport • Conservation of mass • Conservation of energy
Degenerate Matter
Matter in the He core has no energy source left.
Not enough thermal pressure to resist and
balance gravity
Matter assumes a new state, called
star Red Giant
Expansion onto the Giant Branch
Expansion and surface cooling during the phase of an inactive He core and a H- burning shell
Sun will expand beyond Earth’s orbit!
Fusion stops at formation of C,O core.
fusing H to He.
Finite supply of H => finite life time
Evolution on the Main Sequence (2)
A star’s life time T ~ energy reservoir / luminosity
Energy reservoir ~ M
Many have been detected in star forming regions like the Orion Nebula.
Evolution on the Main Sequence (1)
Zero-Age Main Sequence (ZAMS)
Main-Sequence stars live by
Mmax ~ 100 solar masses
a) More massive clouds fragment into b) Very massive stars lose smaller pieces during star formation. mass in strong stellar winds
• How can astronomers study the inside of stars?
This chapter is about how stars live. The next two chapters are about how stars die and the strange objects they leave behind.
C burning: 6.99 s
11 12 1
10
2
9
Hale Waihona Puke 384765
H He He C, O
C Ne, Na, Mg, O Ne O, Mg
Ne burning: 6 ms
23:59:59.996
The Life “Clock” of a Massive Star (3)
H He He C, O
A star’s mass (and chemical composition) completely determines its properties.
That’s why stars initially all line up along the main sequence.
Maximum Masses of Main-Sequence Stars
• What happens as a star uses up its hydrogen?
• What happens when a star exhausts its hydrogen?
• What evidence do astronomers have that stars really do evolve?
Summary of Post Main-Sequence Evolution of Stars
Supernova
Fusion proceeds; formation of Fe core.
Evolution of
4 - 8 Msun stars is still
uncertain.
M>8 Msun
H burning continues in a shell around the core.
He Core + H-burning shell produce more energy than needed for pressure support
Expansion and cooling of the outer layers of the
Chapter 12 Stellar Evolution
Guidepost
Stars form from the interstellar medium and reach stability fusing hydrogen in their cores. This chapter is about the long, stable middle age of stars on the main sequence and their old age as they swell to become giant stars. Here you will answer three essential questions:
Example: Eta Carinae: Binary system of a 60 Msun and 70 Msun star Dramatic mass loss; major eruption in 1843 created double lobes
Minimum Mass of Main-Sequence Stars
Guidepost (continued)
Stars evolve over billions of years because of changes deep inside. That raises an interesting question about how scientists can understand such processes:
Outline
I. Main-Sequence Stars A. Stellar Models B. Why is there a Main Sequence? C. The Upper End of the Main Sequence D. The Lower End of the Main Sequence E. The Life of a Main-Sequence Star F. The Life Expectancies of Stars
Luminosity L ~ M3.5
T ~ M/L ~ 1/M2.5
Massive stars have short lives!