Jupiter 木星(英)
文章来源: 文章作者: 发布时间:2008-07-30 03:06 字体: [ ]  进入论坛
(单词翻译:双击或拖选)

    Jupiter is the fifth planet from the Sun and by far the largest. Jupiter is more than twice as massive as all the other planets combined (the mass of Jupiter is 318 times that of Earth).

    orbit:    778,330,000 km (5.20 AU) from Sun

    diameter: 142,984 km (equatorial)

    mass:     1.900e27 kg

    Jupiter (a.k.a. Jove; Greek Zeus) was the King of the Gods, the ruler of Olympus and the patron of the Roman state. Zeus was the son of Cronus (Saturn1).

    Jupiter is the fourth brightest object in the sky (after the Sun, the Moon and Venus). It has been known since prehistoric2 times as a bright "wandering star". But in 1610 when Galileo first pointed3 a telescope at the sky he discovered Jupiter's four large moons Io, Europa, Ganymede and Callisto (now known as the Galilean moons) and recorded their motions back and forth4 around Jupiter. This was the first discovery of a center of motion not apparently5 centered on the Earth. It was a major point in favor of Copernicus's heliocentric theory of the motions of the planets (along with other new evidence from his telescope: the phases of Venus and the mountains on the Moon). Galileo's outspoken6 support of the Copernican theory got him in trouble with the Inquisition. Today anyone can repeat Galileo's observations (without fear of retribution :-) using binoculars7 or an inexpensive telescope.

    Jupiter was first visited by Pioneer 10 in 1973 and later by Pioneer 11, Voyager 1, Voyager 2 and Ulysses. The spacecraft Galileo orbited Jupiter for eight years. It is still regularly observed by the Hubble Space Telescope.

    The gas planets do not have solid surfaces, their gaseous8 material simply gets denser9 with depth (the radii10 and diameters quoted for the planets are for levels corresponding to a pressure of 1 atmosphere). What we see when looking at these planets is the tops of clouds high in their atmospheres (slightly above the 1 atmosphere level).

    Jupiter is about 90% hydrogen and 10% helium (by numbers of atoms, 75/25% by mass) with traces of methane11, water, ammonia and "rock". This is very close to the composition of the primordial12 Solar Nebula13 from which the entire solar system was formed. Saturn has a similar composition, but Uranus14 and Neptune15 have much less hydrogen and helium.

    Our knowledge of the interior of Jupiter (and the other gas planets) is highly indirect and likely to remain so for some time. (The data from Galileo's atmospheric16 probe goes down only about 150 km below the cloud tops.)

    Jupiter probably has a core of rocky material amounting to something like 10 to 15 Earth-masses.

    Above the core lies the main bulk of the planet in the form of liquid metallic17 hydrogen. This exotic form of the most common of elements is possible only at pressures exceeding 4 million bars, as is the case in the interior of Jupiter (and Saturn). Liquid metallic hydrogen consists of ionized protons and electrons (like the interior of the Sun but at a far lower temperature). At the temperature and pressure of Jupiter's interior hydrogen is a liquid, not a gas. It is an electrical conductor and the source of Jupiter's magnetic field. This layer probably also contains some helium and traces of various "ices".

    The outermost18 layer is composed primarily of ordinary molecular19 hydrogen and helium which is liquid in the interior and gaseous further out. The atmosphere we see is just the very top of this deep layer. Water, carbon dioxide, methane and other simple molecules20 are also present in tiny amounts.

    Recent experiments have shown that hydrogen does not change phase suddenly. Therefore the interiors of the jovian planets probably have indistinct boundaries between their various interior layers.

    Three distinct layers of clouds are believed to exist consisting of ammonia ice, ammonium hydrosulfide and a mixture of ice and water. However, the preliminary results from the Galileo probe show only faint indications of clouds (one instrument seems to have detected the topmost layer while another may have seen the second). But the probe's entry point (left) was unusual -- Earth-based telescopic observations and more recent observations by the Galileo orbiter suggest that the probe entry site may well have been one of the warmest and least cloudy areas on Jupiter at that time.

    Data from the Galileo atmospheric probe also indicate that there is much less water than expected. The expectation was that Jupiter's atmosphere would contain about twice the amount of oxygen (combined with the abundant hydrogen to make water) as the Sun. But it now appears that the actual concentration much less than the Sun's. Also surprising was the high temperature and density21 of the uppermost parts of the atmosphere.

    Jupiter and the other gas planets have high velocity22 winds which are confined in wide bands of latitude23. The winds blow in opposite directions in adjacent bands. Slight chemical and temperature differences between these bands are responsible for the colored bands that dominate the planet's appearance. The light colored bands are called zones; the dark ones belts. The bands have been known for some time on Jupiter, but the complex vortices in the boundary regions between the bands were first seen by Voyager. The data from the Galileo probe indicate that the winds are even faster than expected (more than 400 mph) and extend down into as far as the probe was able to observe; they may extend down thousands of kilometers into the interior. Jupiter's atmosphere was also found to be quite turbulent. This indicates that Jupiter's winds are driven in large part by its internal heat rather than from solar input24 as on Earth.

    The vivid colors seen in Jupiter's clouds are probably the result of subtle chemical reactions of the trace elements in Jupiter's atmosphere, perhaps involving sulfur25 whose compounds take on a wide variety of colors, but the details are unknown.

    The colors correlate with the cloud's altitude: blue lowest, followed by browns and whites, with reds highest. Sometimes we see the lower layers through holes in the upper ones.

    The Great Red Spot (GRS) has been seen by Earthly observers for more than 300 years (its discovery is usually attributed to Cassini, or Robert Hooke in the 17th century). The GRS is an oval about 12,000 by 25,000 km, big enough to hold two Earths. Other smaller but similar spots have been known for decades. Infrared26 observations and the direction of its rotation27 indicate that the GRS is a high-pressure region whose cloud tops are significantly higher and colder than the surrounding regions. Similar structures have been seen on Saturn and Neptune. It is not known how such structures can persist for so long.

    Jupiter radiates more energy into space than it receives from the Sun. The interior of Jupiter is hot: the core is probably about 20,000 K. The heat is generated by the Kelvin-Helmholtz mechanism28, the slow gravitational compression of the planet. (Jupiter does NOT produce energy by nuclear fusion29 as in the Sun; it is much too small and hence its interior is too cool to ignite nuclear reactions.) This interior heat probably causes convection deep within Jupiter's liquid layers and is probably responsible for the complex motions we see in the cloud tops. Saturn and Neptune are similar to Jupiter in this respect, but oddly, Uranus is not.

    Jupiter is just about as large in diameter as a gas planet can be. If more material were to be added, it would be compressed by gravity such that the overall radius30 would increase only slightly. A star can be larger only because of its internal (nuclear) heat source. (But Jupiter would have to be at least 80 times more massive to become a star.)

    Jupiter has a huge magnetic field, much stronger than Earth's. Its magnetosphere extends more than 650 million km (past the orbit of Saturn!). (Note that Jupiter's magnetosphere is far from spherical31 -- it extends "only" a few million kilometers in the direction toward the Sun.) Jupiter's moons therefore lie within its magnetosphere, a fact which may partially32 explain some of the activity on Io. Unfortunately for future space travelers and of real concern to the designers of the Voyager and Galileo spacecraft, the environment near Jupiter contains high levels of energetic particles trapped by Jupiter's magnetic field. This "radiation" is similar to, but much more intense than, that found within Earth's Van Allen belts. It would be immediately fatal to an unprotected human being.

    The Galileo atmospheric probe discovered a new intense radiation belt between Jupiter's ring and the uppermost atmospheric layers. This new belt is approximately 10 times as strong as Earth's Van Allen radiation belts. Surprisingly, this new belt was also found to contain high energy helium ions of unknown origin.

    Jupiter has rings like Saturn's, but much fainter and smaller (right). They were totally unexpected and were only discovered when two of the Voyager 1 scientists insisted that after traveling 1 billion km it was at least worth a quick look to see if any rings might be present. Everyone else thought that the chance of finding anything was nil33, but there they were. It was a major coup34. They have since been imaged in the infra-red from ground-based observatories35 and by Galileo.

    Unlike Saturn's, Jupiter's rings are dark (albedo about .05). They're probably composed of very small grains of rocky material. Unlike Saturn's rings, they seem to contain no ice.

    Particles in Jupiter's rings probably don't stay there for long (due to atmospheric and magnetic drag). The Galileo spacecraft found clear evidence that the rings are continuously resupplied by dust formed by micrometeor impacts on the four inner moons, which are very energetic because of Jupiter's large gravitational field. The inner halo ring is broadened by interactions with Jupiter's magnetic field.

    In July 1994, Comet Shoemaker-Levy 9 collided with Jupiter with spectacular results (left). The effects were clearly visible even with amateur telescopes. The debris36 from the collision was visible for nearly a year afterward37 with HST.

    When it is in the nighttime sky, Jupiter is often the brightest "star" in the sky (it is second only to Venus, which is seldom visible in a dark sky). The four Galilean moons are easily visible with binoculars; a few bands and the Great Red Spot can be seen with a small astronomical38 telescope. There are several Web sites that show the current position of Jupiter (and the other planets) in the sky. More detailed39 and customized charts can be created with a planetarium40 program.

    Jupiter's Satellites

    Jupiter has 63 known satellites (as of Feb 2004): the four large Galilean moons plus many more small ones some of which have not yet been named:

    Jupiter is very gradually slowing down due to the tidal drag produced by the Galilean satellites. Also, the same tidal forces are changing the orbits of the moons, very slowly forcing them farther from Jupiter.

    Io, Europa and Ganymede are locked together in a 1:2:4 orbital resonance41 and their orbits evolve together. Callisto is almost part of this as well. In a few hundred million years, Callisto will be locked in too, orbiting at exactly twice the period of Ganymede (eight times the period of Io).

    Jupiter's satellites are named for other figures in the life of Zeus (mostly his numerous lovers).

    Many more small moons have been discovered recently but have not as yet been officially confirmed or named. The most up to date info on them can be found at Scott Sheppard's site.

    Distance  Radius    Mass

    Satellite  (000 km)   (km)     (kg)   Discoverer   Date

    ---------   --------    ------    -------  ----------     -----

    Metis           128      20  9.56e16  Synnott      1979

    Adrastea        129      10  1.91e16  Jewitt       1979

    Amalthea        181      98  7.17e18  Barnard      1892

    Thebe           222      50  7.77e17  Synnott      1979

    Io                 422    1815  8.94e22  Galileo      1610

    Europa          671    1569  4.80e22  Galileo      1610

    Ganymede       1070    2631  1.48e23  Galileo      1610

    Callisto       1883    2400  1.08e23  Galileo      1610

    Leda          11094       8  5.68e15  Kowal        1974

    Himalia       11480      93  9.56e18  Perrine      1904

    Lysithea      11720      18  7.77e16  Nicholson    1938

    Elara         11737      38  7.77e17  Perrine      1905

    Ananke        21200      15  3.82e16  Nicholson    1951

    Carme         22600      20  9.56e16  Nicholson    1938

    Pasiphae      23500      25  1.91e17  Melotte      1908

    Sinope        23700      18  7.77e16  Nicholson    1914

    Values for the smaller moons are approximate. Many more small moons are not listed here.

    Jupiter's Rings

    Distance   Width   Mass

    Ring      (km)        (km)   (kg)

    ----      --------   -----  ------

    Halo      100000     22800   ?

    Main      122800      6400  1e13

    Gossamer  129200    214200   ?

    (distance is from Jupiter's center to the ring's inner edge)



点击收听单词发音收听单词发音  

1 Saturn tsZy1     
n.农神,土星
参考例句:
  • Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪,为什么只有土星有光环。
  • These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们,土星由较轻的物质构成。
2 prehistoric sPVxQ     
adj.(有记载的)历史以前的,史前的,古老的
参考例句:
  • They have found prehistoric remains.他们发现了史前遗迹。
  • It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。
3 pointed Il8zB4     
adj.尖的,直截了当的
参考例句:
  • He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
4 forth Hzdz2     
adv.向前;向外,往外
参考例句:
  • The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
  • He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。
5 apparently tMmyQ     
adv.显然地;表面上,似乎
参考例句:
  • An apparently blind alley leads suddenly into an open space.山穷水尽,豁然开朗。
  • He was apparently much surprised at the news.他对那个消息显然感到十分惊异。
6 outspoken 3mIz7v     
adj.直言无讳的,坦率的,坦白无隐的
参考例句:
  • He was outspoken in his criticism.他在批评中直言不讳。
  • She is an outspoken critic of the school system in this city.她是这座城市里学校制度的坦率的批评者。
7 binoculars IybzWh     
n.双筒望远镜
参考例句:
  • He watched the play through his binoculars.他用双筒望远镜看戏。
  • If I had binoculars,I could see that comet clearly.如果我有望远镜,我就可以清楚地看见那颗彗星。
8 gaseous Hlvy2     
adj.气体的,气态的
参考例句:
  • Air whether in the gaseous or liquid state is a fluid.空气,无论是气态的或是液态的,都是一种流体。
  • Freon exists both in liquid and gaseous states.氟利昂有液态和气态两种形态。
9 denser denser     
adj. 不易看透的, 密集的, 浓厚的, 愚钝的
参考例句:
  • The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民,对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
  • As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时,发现人群相当密集。
10 radii 736eba6ae8f603ee16e88a83cdc35f90     
n.半径;半径(距离)( radius的名词复数 );用半径度量的圆形面积;半径范围;桡骨
参考例句:
  • Hence, the damage radii can not be determined from overpressure alone. 因此,破坏半径不能单单由超压力大小来决定。 来自辞典例句
  • It is now necessary to introduce a sign convention for radii of curvature. 现在必须介绍曲率半径的正负号规则。 来自辞典例句
11 methane t1Eyx     
n.甲烷,沼气
参考例句:
  • The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • Methane may have extraterrestrial significance.甲烷具有星际意义。
12 primordial 11PzK     
adj.原始的;最初的
参考例句:
  • It is the primordial force that propels us forward.它是推动我们前进的原始动力。
  • The Neanderthal Man is one of our primordial ancestors.的尼安德特人是我们的原始祖先之一.
13 nebula E55zw     
n.星云,喷雾剂
参考例句:
  • A powerful telescope can resolve a nebula into stars.一架高性能的望远镜能从星云中分辨出星球来。
  • A nebula is really a discrete mass of innumerous stars.一团星云实际上是无数星体不连续的集合体。
14 Uranus 3pZyA     
n.天王星
参考例句:
  • Uranus is unusual because it is tilted.天王星非常特殊,因为它是倾斜的。
  • Uranus represents sudden change and rebellion.天王星代表突然性的改变和反叛。
15 Neptune LNezw     
n.海王星
参考例句:
  • Neptune is the furthest planet from the sun.海王星是离太阳最远的行星。
  • Neptune turned out to be a dynamic,stormy world.海王星原来是个有生气、多风暴的世界。
16 atmospheric 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
17 metallic LCuxO     
adj.金属的;金属制的;含金属的;产金属的;像金属的
参考例句:
  • A sharp metallic note coming from the outside frightened me.外面传来尖锐铿锵的声音吓了我一跳。
  • He picked up a metallic ring last night.昨夜他捡了一个金属戒指。
18 outermost w4fzc     
adj.最外面的,远离中心的
参考例句:
  • He fired and hit the outermost ring of the target.他开枪射中了靶子的最外一环。
  • The outermost electron is shielded from the nucleus.原子核对最外层电子的作用受到屏蔽。
19 molecular mE9xh     
adj.分子的;克分子的
参考例句:
  • The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
20 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
21 density rOdzZ     
n.密集,密度,浓度
参考例句:
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
22 velocity rLYzx     
n.速度,速率
参考例句:
  • Einstein's theory links energy with mass and velocity of light.爱因斯坦的理论把能量同质量和光速联系起来。
  • The velocity of light is about 300000 kilometres per second.光速约为每秒300000公里。
23 latitude i23xV     
n.纬度,行动或言论的自由(范围),(pl.)地区
参考例句:
  • The latitude of the island is 20 degrees south.该岛的纬度是南纬20度。
  • The two cities are at approximately the same latitude.这两个城市差不多位于同一纬度上。
24 input X6lxm     
n.输入(物);投入;vt.把(数据等)输入计算机
参考例句:
  • I will forever be grateful for his considerable input.我将永远感激他的大量投入。
  • All this information had to be input onto the computer.所有这些信息都必须输入计算机。
25 sulfur ps4wC     
n.硫,硫磺(=sulphur)
参考例句:
  • Sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
  • Burning may produce sulfur oxides.燃烧可能会产生硫氧化物。
26 infrared dx0yp     
adj./n.红外线(的)
参考例句:
  • Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
  • Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。
27 rotation LXmxE     
n.旋转;循环,轮流
参考例句:
  • Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
  • The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。
28 mechanism zCWxr     
n.机械装置;机构,结构
参考例句:
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
29 fusion HfDz5     
n.溶化;熔解;熔化状态,熔和;熔接
参考例句:
  • Brass is formed by the fusion of copper and zinc. 黄铜是通过铜和锌的熔合而成的。
  • This alloy is formed by the fusion of two types of metal.这种合金是用两种金属熔合而成的。
30 radius LTKxp     
n.半径,半径范围;有效航程,范围,界限
参考例句:
  • He has visited every shop within a radius of two miles.周围两英里以内的店铺他都去过。
  • We are measuring the radius of the circle.我们正在测量圆的半径。
31 spherical 7FqzQ     
adj.球形的;球面的
参考例句:
  • The Earth is a nearly spherical planet.地球是一个近似球体的行星。
  • Many engineers shy away from spherical projection methods.许多工程师对球面投影法有畏难情绪。
32 partially yL7xm     
adv.部分地,从某些方面讲
参考例句:
  • The door was partially concealed by the drapes.门有一部分被门帘遮住了。
  • The police managed to restore calm and the curfew was partially lifted.警方设法恢复了平静,宵禁部分解除。
33 nil 7GgxO     
n.无,全无,零
参考例句:
  • My knowledge of the subject is practically nil.我在这方面的知识几乎等于零。
  • Their legal rights are virtually nil.他们实际上毫无法律权利。
34 coup co5z4     
n.政变;突然而成功的行动
参考例句:
  • The monarch was ousted by a military coup.那君主被军事政变者废黜了。
  • That government was overthrown in a military coup three years ago.那个政府在3年前的军事政变中被推翻。
35 observatories d730b278442c711432218e89314e2a09     
n.天文台,气象台( observatory的名词复数 )
参考例句:
  • John Heilbron, The Sun in the Church: Cathedrals as Solar Observatories, 3-23. 约翰.海耳布隆,《教会里的太阳:教堂即太阳观测台》,第3-23页。 来自互联网
  • Meteorologists use satellites, land observatories and historical data to provide information about the weather. 气象学家使用卫星、上天文台和历史资料来提供有关天气的信息。 来自互联网
36 debris debris     
n.瓦砾堆,废墟,碎片
参考例句:
  • After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
  • Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上,导致蛀牙。
37 afterward fK6y3     
adv.后来;以后
参考例句:
  • Let's go to the theatre first and eat afterward. 让我们先去看戏,然后吃饭。
  • Afterward,the boy became a very famous artist.后来,这男孩成为一个很有名的艺术家。
38 astronomical keTyO     
adj.天文学的,(数字)极大的
参考例句:
  • He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
  • Houses in the village are selling for astronomical prices.乡村的房价正在飙升。
39 detailed xuNzms     
adj.详细的,详尽的,极注意细节的,完全的
参考例句:
  • He had made a detailed study of the terrain.他对地形作了缜密的研究。
  • A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。
40 planetarium y20z0     
n.天文馆;天象仪
参考例句:
  • The planetarium staff also prepared talks for radio broadcast.天文馆的工作人员还要准备讲稿给电台广播。
  • It landed in a shallow basin fifty yards from the planetarium.它降落在离天文馆五十码处的一个浅盆地中。
41 resonance hBazC     
n.洪亮;共鸣;共振
参考例句:
  • Playing the piano sets up resonance in those glass ornaments.一弹钢琴那些玻璃饰物就会产生共振。
  • The areas under the two resonance envelopes are unequal.两个共振峰下面的面积是不相等的。
TAG标签:
发表评论
请自觉遵守互联网相关的政策法规,严禁发布色情、暴力、反动的言论。
评价:
表情:
验证码:点击我更换图片