冀教版英语九年级上册Unit 5 Look into Science背景知识：太阳系相关知识

1、 5/5背景知识：太阳系相关知识150亿年前的宇宙大爆炸诞生了宇宙，宇宙开始膨胀，并慢慢变冷，孕育了包括我们在内的太阳系。 科学家预言，不用50亿年，太阳开始逐渐膨胀并慢慢消亡，使太阳系陷入永恒的寒冷和黑暗之中。因此，要想在太阳系外寻找人类新的住所，就必须先对我们的太阳系有足够的了解。1962年12月14日，美国“水手2号”航天探测器执行的近金星探测飞行使命标志着对行星及新的星系探索的开始。 在远古的时候，人们就注意到天上许多星星的相对位置是恒定不变的。但有5颗亮星却在众星之间不断地移动。因此人们把“动”的星星称为“行星”，“不动”的星星称为“恒星”，并给行星各自起了名字，即：水星、金星、火星

2、、木星和土星。其中水星也称辰星，它最靠近太阳，不超过一辰（30度）。金星又叫太白星或启明星、长庚星。它光彩夺目，是全天最亮的星；火星又称“荧惑”，因它的火红颜色而得名；木星也称岁星，它大约12年运行一周天，每年差不多行经一次（全天分成十二次），古代用它来纪年；土星也称镇星或填星，因为它大约28年运行一周天，一年镇守一宿（中国古代把全天分成二十宿）。这就是人们肉眼能看见的五大行星，中国古代统称它们为“五星”，再加上太阳、月亮总称为“七曜”。 近两个世纪以来，天文学家又发现了3颗大行星（天王星、海王星和冥王星）。这样，包括地球在内的9颗行星就构成了一个围绕太阳旋转的行星系统。离太阳最近的行星是水星

3、，以下依次是金星、地球、火星、木星、土星、天王星、海王星和冥王星。除了水星和金星之外，所有的行星都有卫星。在火星和木星之间存在着数十万颗大小不等、形状各异的小行星，天文学家把这个区域称为小行星带。此外，太阳系中还有许许多多的彗星、流星以及稀薄的微尘粒和气体等。 太阳质量占太阳系总质量的99.8，它以自己强大的引力将太阳系里的所有天体牢牢地吸引在它的周围，使它们不离不散、井然有序地绕自己旋转。同时，太阳又作为一颗普通恒星，带领它的成员，万古不息地绕银河系的中心运动。 太阳系起源包含两个基本问题：太阳系中形成行星的物质从何而来和行星是怎样形成的。围绕这两个问题，产生了各种各样的学说。 1755年，

4、德国哲学家康德(Immanuel Kant)首先提出了太阳系起源的星云假说。他认为，太阳系是由原始星云按照万有引力定律演化而成。在这个原始星云中，大小不等的固体微粒在万有引力的作用下相互接近，大微粒吸引小微粒形成较大的团块，团块又陆续把周围的微粒吸引过来，这样，团块越来越大，而“天体在吸引最强的地方开始形成”。引力最强的中心部分吸引的物质最多，先形成太阳。外面的微粒在太阳吸引下向其下落时，与其它微粒碰撞而改变方向，变成绕太阳作圆周运动；运动中的微粒又逐渐形成引力中心，最后凝聚成朝同一方向转动的行星。41年后，法国著名的数学家和天文学家拉普拉斯（Pierre Simon Laplace）也独立提

5、出了关于太阳系起源的星云假说。与康德的星云说不同之处在于，他认为太阳系是由炽热气体组成的星云形成的。气体由于冷却而收缩，因此自转加快，离心力也随之增大，于是星云变得十分扁平。在星云外缘，离心力超过引力的时候便分离出一个圆环，这样反复分离成许多环。圆环由于物质分布不均匀而进一步收缩，形成行星，中心部分形成太阳。继星云说之后，又相继出现了“灾变说”、“俘获说”等理论。 随着现代天体物理学和物理学的发展，特别是恒星演化理论的建立，产生了现代星云说，并逐渐占了主导地位。现代星云假说根据观测资料和理论计算，提出它的主要观点：太阳系原始星云是巨大的星际云瓦解的一个小云，一开始就在自转，并在自身引力作用下收

6、缩，中心部分形成太阳，外部演化成星云盘，星云盘以后形成行星。目前，现代星云说又存在不同学派，这些学派之间还存在着许多差别，有待进一步研究和证实。 八大行星简介1.THE PLANETS 行星Although we live in a very small piece of the Universe, its still where we call home and its a very interesting place. The nine planets that make up our solar system range from very tiny rocky planets to h

7、uge gas giants featuring fascinating ring systems. Mercury 水星Mercury is the closest planet to the Sun. Its surface has many thousands of impact craters as a result of being bombarded by objects since the solar systems early days. Since Mercury has no protective atmosphere, the temperature on the sur

8、face ranges from extremely hot on the side facing the Sun to extremely cold on the side that faces away from the Sun. Venus 金星（太白星）Venus is named after the Roman goddess of love and beauty. This is one of those cases where beauty is only skin deep, though, as the surface of Venus is a very unpleasan

9、t place featuring very high temperatures, winds that blow hundreds of miles per hour and an atmosphere of sulfuric acid. Venus is an example of runaway greenhouse effect on a planetary scale. Earth 地球People always say theres no place like home. Our home planet is a very beautiful place with the most

10、 varied surface in the entire solar system. From a distance, our planet looks like a beautiful big blue marble. Mars 火星 The Red Planet is named after the Roman god of war. Its distinctive rust color is easily seen through a small telescope. The surface of Mars features many mountains, canyons and ev

11、en polar ice caps that look a lot like those here on Earth. In ancient times, Mars may have harbored some kind of life, and there is a lot of research going on now trying to get a definitive answer as to whether we are the only life forms in the solar system. Jupiter 木星Jupiter is the largest planet

12、in our solar system. It has at least sixty-one moons and features the Great Red Spot, which is a huge storm that has been observed from here on Earth for over three hundred years. Saturn 土星Saturn is one of the most beautiful planets in the solar system. Its fascinating system of rings have been a so

13、urce of wonder since we first saw them with the earliest telescopes. Although the rings look fairly simple through a small telescope, spacecraft pictures have revealed that what looks like two rings through a telescope is actually hundreds of individual ring systems. In addition, Saturn has so many

14、moons that it is like a miniature solar system. Uranus天王星Uranus is one of the giant gas planets in the solar system. Its mysterious blue-green color provides very few clues as to what is going on underneath the surface clouds. Uranus also has a very faint ring system that we didnt know existed until

15、 the planet was visited by the Voyager spacecraft. Neptune 海王星Neptune was the last stop the Voyager mission made before if left our solar system. What we found out from Voyager was that Neptune has winds that blow hundreds of miles per hour and a moon that features geysers of nitrogen that erupt and

16、 leave dark marks on the surface. Pluto 冥王星Pluto is the smallest and most mysterious planet in our solar system. Pluto is so far away that the Sun is just a dim point of light that looks a lot like any other star. Pluto has one moon, Charon, which is almost as big as the planet itself. 2. The Big Ba

17、ng Theory 大爆炸理论 The Big Bang Theory is the dominant scientific theory about the origin of the universe. According to the big bang, the universe was created sometime between 10 billion and 20 billion years ago from a cosmic explosion that hurled matter and in all directions. In 1927, the Belgian prie

18、st Georges Lemaire was the first to propose that the universe began with the explosion of a primeval atom. His proposal came after observing the red shift in distant nebulas by astronomers to a model of the universe based on relativity. Years later, Edwin Hubble found experimental evidence to help justify Lemaires theory. He found that distant galaxies in every direction are going away from us with